Another thing occurred to me as I was re-reading the full post: another possibility is that padding on the plunger for the edit button came off and is stuck on the board causing the button to be permanently pressed.
I got all of that taken apart, made sure none of the soft buttons were permanently pressed or their conductive parts mucked up. Nothing there.
So I ended up shorting the wire grids you speak of. I found that I could actuate every button except for the PROGRAM button.
NOTE: just to be sure it's clear, I started this thread saying that the EDIT button was stuck, but that's not the case. It turns out that I could get into the SYSTEM, STORE, EDIT, and all other buttons except PROGRAM. So the statement "can't get out of EDIT mode" is still mostly true, but only because the PROGRAM button is the faulty one (meaning I can't change patches/programs, so forever in Edit mode).
Also, the KNOB is wonky (this unit took a fall once), so I could use the entire assembly, which is listed as Item 14 on page 8-49 of the service manual. On page 8-51, it's listed as Part #750-11565.
Digikey doesn't seem to have any Lexicon parts (they aren't listed on http://www.digikey.com/en/supplier-centers
). The part number doesn't turn up anything.
Should I contact Lexicon through their web site? They seem to want to point me to service centers, which means parts mark-up and labor, perhaps shipping.
I'm not currently employed and this is a plug-in part, so I can do this work myself if the part is affordable enough.