The Plastic plate with the driver comes out fairly easily with a small flat head screw driver. There are small gaps to wedge the blade in and start prying up the plate. This job goes MUCH easier if you pop the head band off of each cup as you work on it. I got the driver assembly plate out in about 90 seconds, so it should not be tough. Add some heat from a hair dryer or heat lamp or something for a few minutes if you have trouble.
The next layer is pictured below. You only need to take this ring out if you want to clean the whole thing/ replace the fabric liner for the vents. I had the worst time trying to get this ring out and I was almost certain that I was going to break something in the process. In fact, I made some light damage to one of the vent slats and actually broke one of my small screw drivers. Keep reading for advice on how to avoid that.
Below is the heat lamp setup I used. I used it in the kitchen because I hate my counters and I would not have been sad to see them melt/ burn. I sat the heat lamp in front of each for about 27 minutes (30 minutes was too long) before working on it. They cool off pretty quickly, so you may have to reheat it if you are too slow.
I had to find the only gap in retaining ledges where I could wedge a super small screw driver. I popped it up a little, just over the ledge, then I pressed on the ring from the outside through the vent slats. This is where I made a mistake. I used a screw driver with a shaft wider than the slat opening. I would use something like a popsicle stick instead.
Here I am starting to pry up the ring and run my tool (from my nail kit. I don't know what it is but it worked pretty good.) around the ring where it meets the can. Avoid overusing the screw driver on this, I scratched up the inside pretty good during this process before I starting using the flatter tool. I had to pry the ring from under the retaining ledge on the second retainer. I would do at least one of the lower retainers either first or second so that you can simply bend the ring and wiggle it out from the other two retainers.
All broken down. Got that pesky dirty grey fabric out, too!
I decided to add some flair and went to the fabric store to replace the grey stuff. I found some grey stuff but not the same hue, so I decided to just change colors. I got basically the same fabric but in red. The type of fabric is called "Jet" something and I got it at Joann Fabric. I used the inner cup as a stencil and cut rings. Then, I decided I was sick of looking at the metal barrier to the driver, so I used the driver assembly ring as another stencil and slipped that fabric on top of the black felt ring and then fastened the headphone pads over that. I did not want to glue it and it looks ok, but I will figure out something more permanent later.
Next I will beef up the head band, look at some brown leather options for custom pads, and then recable it with custom detachable cables. Also, cleaning it out, adding the fabric, and letting them get a few hours of use has really brought this things back to life; they sound great. I like them way more than my DT770/80 now. The sounds are a lot less dimensional than that pair though.
