Hey, my Dad sent me my childhood in a box, which included a 2600 (which I got working), a 400 computer with tape drive, and 800XL with floppy drive. The 800XL powers up and goes to the input screen, and I can get cartridges to work on it, and I even got my graphics tablet to work!
However, the 800XL's keyboard is not working on some keys. I believe it is a type 3 (non-mylar) keyboard. I tried just mashing the non-working keys repeatedly but to no avail. I opened up the whole thing for cleaning and while inside I followed the advice elsewhere of swapping the 4501 keyboard IC's to see if one of them was going bad. That produced no change, and about a third of the keys still refuse to work.
Is it possible the switches just need cleaning? Is it easy to pop off the keys and clean them somehow? Or will it require more effort that will involve soldering? I've done a little bit of that, but I wouldn't be super confident doing it myself.
Anything else I can try? Thanks!