I just wanted to add another person out here in the Bay Area, if Willy Hermann is not an option: Paul Strickland runs a repair shop in Daly City. He goes by clamsterdamm over on Tapeheads.
I bought a ZX-7 from another Tapehead member in San Jose, and it worked fine for a bunch of cassette transfers. I lent it to the owner of those cassettes (long story), and he accidentally broke the door. I could still load a cassette by aligning it, but after a few more plays, I stopped getting audio.
Fortunately, I found Paul, and he took the deck in. He fixed the door, and the playback issue was caused by aging, deteriorating capacitors (Orange Cap Disease), so he replaced them. I also asked him to replace the unaffected ones. He replaced the belts, tuned it up, etc. I thought his price for parts and labor was pretty reasonable - $400.
Paul Strickland
408-507-4890