Been lurking at this thread from the beginning almost. :-)
Want to thank Chinsetta and Tachikoma, and others contributing to this thread.
Have a pair of 404's that in one side didn't sing much.
The driver has been re-coated. And now sings again :-)
As Tachikoma has recommended quite a few times I wasn't shy applying the coating. Used a micro fiber cloth to rub/polish the mylar as I didn't have a proper sponge.
No squeling, buzzing and I could play rather loud until the 212 sort of gave in.
I use some tape with mild adhesive to cleanup the stators before assembling. Seems to work fine.
I will glue the driver today and the it takes about 24 hours to harden up.
So I guess I'll have the final result in a few days.
The most tricky part of this seems to be cracking the driver open without messing up. I use a rather big Stanley knif with fresh blade, and a lot of patients ... but it does take a while to crack it open as for my experience.
Thanks again for all the contribution