I'm so glad that you were able to perform the mod, and that you like the results!
To help others considering this mod, how difficult would you say it was to perform (once you had the required materials ie washers and Lazer Bond glue)?
Yup, Lazer Bond is amazing stuff. So easy to work with due to it's syringe-like applicator, instant drying, and dirt cheap cost.
It's the glue I use about 97% of the time when modding IEMs.
The important thing you have to remember about it is that it can ONLY be used where the UV light can "reach" the glue to cure it. For example, if you tried to glue a coin to a piece of wood using a blob of Lazer Bond in the center of the coin, it wouldn't work. The UV light can't reach it after you stick the coin to the wood. If you tried to glue 2 pieces of clear glass together, it WOULD work because the UV light CAN reach the glue.
So with regards to IEM mods, Lazer Bond works great for things like filling IEM vent holes, because you can do it all from the outside of the IEM - just put a small drop on the vent hole and cure it with the UV light.
For the washer mod on the ZS6, you have to use the Lazer Bond on the "outside" of the washer - the perfect place is where the edge of the ZS6 nozzle lip meets the washer. I drew a few very crude illustrations to show what I mean:
This method
WILL work because the curing light CAN reach the glue (click for larger view):
This method
will NOT work, because the curing light can NOT reach the glue through the opaque surfaces (click for larger view):