[FYLegend]

  I think what you're  experiencing is something I commonly experienced with the IM50 when I first got it.
What I found it to be was sinking, due to your canals, since they aren't going to be  exactly the same in both ears(mine are), the stem of the IEM itself will fit in awkwardly, come out as congested, and very flushed sounding.
A little bit of insight though, it's harder to tell if you've never had your canals tested, or you don't own any Custom IEMs, but I think I've narrowed your issue down.

Well it didn't occur with my first pair, so I suspect something may be wrong with the venting, though maybe my ears have changed a bit as I was using Piston 3 for the last few months (which have a lot of venting and shallow insertion). While I sometimes had sealing issues before, just pulling down on the cord solves it, but now if I do that on the right ear the volume just dips as the pressure changes.

 

[ozkan]

  Well it didn't occur with my first pair, so I suspect something may be wrong with the venting, though maybe my ears have changed a bit as I was using Piston 3 for the last few months (which have a lot of venting and shallow insertion). While I sometimes had sealing issues before, just pulling down on the cord solves it, but now if I do that on the right ear the volume just dips as the pressure changes.

 
Is the connector loose which has driver flex? If so I'd recommend you putting a small piece of folded paper into the socket near the pins and secure the connection so the jack on the cable will not move anymore.
 
But you are also free to open a small hole with a needle on the vent. This worked on my IM50 that I shared earlier in this thread.
The sound became more open and detailed after poking a hole.
 
You may try this mod on your old pair and see if it works for you.

 

[FYLegend]

   
Is the connector loose which has driver flex? If so I'd recommend you putting a small piece of folded paper into the socket near the pins and secure the connection so the jack on the cable will not move anymore.

no I just hear a crinkling noise when I insert the right housing into my ear - it doesn't affect the sound but over time the seal feels too tight and there's some pressure. The connector is a little wobbly but not loose.

 

[whitemass]

  Well it didn't occur with my first pair, so I suspect something may be wrong with the venting, though maybe my ears have changed a bit as I was using Piston 3 for the last few months (which have a lot of venting and shallow insertion). While I sometimes had sealing issues before, just pulling down on the cord solves it, but now if I do that on the right ear the volume just dips as the pressure changes.

Either send them in for repair, or have them replaced!
Venting issues have only occurred a select few times with the IM70, but are common, only more common with the IM02 though.
These are the only two models I've really heard genuine complaints from.

 

[FYLegend]

  Either send them in for repair, or have them replaced!
Venting issues have only occurred a select few times with the IM70, but are common, only more common with the IM02 though.
These are the only two models I've really heard genuine complaints from.

I was thinking of that but I need pay for shipping to send it back to the seller, and I'm travelling in the next few weeks so I can't wait for a replacement. Putting it on slightly loose reduces any sort of pressure. I'm gonna play it safe with this pair after what happened to the old one, so they won't be my daily driver but instead my home-listening IEMs (mainly because my phone's headphone jack is wrecked and only works well with the P3s).
 
I've had driver flex on a few other IEMs and they haven't broken on me yet, so I don't know if it's a real problem.
 
This one was bought from eBay so I don't think AT can support the warranty. 
 
@ozkan I think that would help but then I might lose bass on that side.

 

[whitemass]

  I was thinking of that but I need pay for shipping to send it back to the seller, and I'm travelling in the next few weeks so I can't wait for a replacement. Putting it on slightly loose reduces any sort of pressure. I'm gonna play it safe with this pair after what happened to the old one, so they won't be my daily driver but instead my home-listening IEMs (mainly because my phone's headphone jack is wrecked and only works well with the P3s).
 
I've had driver flex on a few other IEMs and they haven't broken on me yet, so I don't know if it's a real problem.
 
This one was bought from eBay so I don't think AT can support the warranty. 
 
@ozkan I think that would help but then I might lose bass on that side.

You should be able to just send it back to AudioTechnica themselves.

 

[ozkan]

  You should be able to just send it back to AudioTechnica themselves.

 
They may ask him to contact with the seller though.

 

[ozkan]

  I was thinking of that but I need pay for shipping to send it back to the seller, and I'm travelling in the next few weeks so I can't wait for a replacement. Putting it on slightly loose reduces any sort of pressure. I'm gonna play it safe with this pair after what happened to the old one, so they won't be my daily driver but instead my home-listening IEMs (mainly because my phone's headphone jack is wrecked and only works well with the P3s).
 
I've had driver flex on a few other IEMs and they haven't broken on me yet, so I don't know if it's a real problem.
 
This one was bought from eBay so I don't think AT can support the warranty. 
 
@ozkan I think that would help but then I might lose bass on that side.

 
When did you buy it? You may still have time to ask for a replacement.

 

[FYLegend]

   
When did you buy it? You may still have time to ask for a replacement.

It arrived yesterday, but I purchased it nearly two weeks ago. 
 
I don't think the driver flex is that much of a problem, it's more the pressure that develops but maybe I'm just too OCD, if I don't pay attention to it it isn't a problem. (I'm quite used to pressure changes with IEMs because I transit up a mountain to school). Now that I recall my old one did have some crinkling on the left ear which may have been driver flex, but it may have just been the eartip - it did go away after some time. I've read some things like try to blow into the nozzle or suck air out of it... don't think it's a good idea though lol
 
Have any of you heard of Vitas? He's a Russian male countertenor-pop singer, the album "Mama" sounds amazing on these (probably the most audiophile-type album of them all, though dynamic range is a bit low, but his recent albums are far worse in dynamics). His voice is ridiculously high in the song "Dedication". The soundstage is really good in that song, but the reverb does seem to add a distortion that's more apparent in the IM70. "Pigtails" also has a really nice soundstage, almost ethereal.

 

[waxall]

I'm using the IM50 and haven't experienced the driver flex issue you've described.  It happens on my other pair of 13mm dynamic custom IEMs though, which are vented.  You might want to have them checked out and replaced.

 

[FYLegend]

  I'm using the IM50 and haven't experienced the driver flex issue you've described.  It happens on my other pair of 13mm dynamic custom IEMs though, which are vented.  You might want to have them checked out and replaced.

I remember Lachlan saying he had driver flex on his IM50 but didn't consider it much of a concern, though not many other users have reported it.
 
If I wasn't travelling in the next few weeks I would probably replace them. My main concern is that the replacement may arrive after I leave and the post office will take it back before I come back. It's not driver flex that is bothering me (if I gently put it in I don't hear it) but there seems to some pressure going into my right ear as a result (it's not a lot and sometimes i don't notice it). I would think that the pressure vent isn't working properly (there is a sticky-foam that covers it up) and maybe moving it around will alleviate the problem.

 

[ozkan]

  I remember Lachlan saying he had driver flex on his IM50 but didn't consider it much of a concern, though not many other users have reported it.
 
If I wasn't travelling in the next few weeks I would probably replace them. It's not driver flex that is bothering me (if I gently put it in I don't hear it) but there seems to some pressure going into my right ear as a result. I would think that the pressure vent isn't working properly (there is a sticky-foam that covers it up) and maybe moving it around will alleviate the problem.

 
Removing the sticky foam in the vent will change the sound. I don't recommend it.

 

[FYLegend]

   
Removing the sticky foam in the vent will change the sound. I don't recommend it.

I just meant loosening it up a little so air can pass through - it seems to me that the driver flex is caused by the sealing and the pressure vent not working properly.. I experimented a little with removing the sticky foam earlier on the damaged housing, it seems to expand the soundstage a lot but also decreases isolation and increases leakage...
 
Also using comply tips can stop the pressure issue I am having but it also drastically alters the sound - treble is more rolled off and everything just sounds duller.

 

[whitemass]

  I remember Lachlan saying he had driver flex on his IM50 but didn't consider it much of a concern, though not many other users have reported it.
 
If I wasn't travelling in the next few weeks I would probably replace them. My main concern is that the replacement may arrive after I leave and the post office will take it back before I come back. It's not driver flex that is bothering me (if I gently put it in I don't hear it) but there seems to some pressure going into my right ear as a result (it's not a lot and sometimes i don't notice it). I would think that the pressure vent isn't working properly (there is a sticky-foam that covers it up) and maybe moving it around will alleviate the problem.

No, it's not common.
And again, it's only really been a complaint on the IM70 a few times, and on the IM01 more than a few.

 

[FYLegend]

Yeah I only saw one other person mention it in a thread, but I only just told him it was driver flex. I guess I will exchange it with the seller and get someone to pick it up if I'm not here. Just hope the replacement doesn't have is problem either... The air pressure is driving me nuts. Even plugging my nose and bowling air out my ears doesn't help (it just seems like the pressure vent is too tightly sealed). My CK323M has a driver flex and air pressure with SHE3590 eartips (best isolation ever) but not as bad as this!
 
EDIT: I sent it back for an exchange.