I was certainly looking at the various Audi EPBs with an idea of repair!
http://forum.a8parts.co.uk/showthread.php?t=13431
I've "repaired" my left EPB at least 3 or 4 times. Taking the back of the EPB, freeing up and cleaning up the crap from it, sealing as best i could and putting back on. Always the left one!!!
I hit the same issue again about a week back and bought one of the Chinese ones off ebay (
https://ebay.us/4OKGtN )as to be honest the plastic casing of the old one was knackered and crumbling. It came with the big O ring seal and a pair of hex screws that are too small and the odd circlip that fits on the piston part where the actuator fits in
I swapped it over. My pads were low so i swapped on a spare pair of those. All went pretty well and things were quieter and seemed to work ok. I still had a pad error but often that sorts itself out.
However on getting home, the car checked the brakes and it errored again.
Today I popped it back off and tried the adjust the brake to the mid point and tried again and actually I'm a bit stumped.
The motor turns, the actuator is the right size, it fits nicely and sounds better, but it seems to run too long and then error. The ampage appears a bit higher but nothing drastic the left is 0.5ish more than the right.
I did pop the old one open and the motor part is potted into the case or i'd have swapped bits over.
I'm a bit confused to be fair why it seems to run longer than the other side and thus error