Amiga 500 repair question

[Boing-ball]

That’s not normal. Looks like you have something failing on the mainboard. You mention A500. Is it a A500 or a A500+ ? If the latter, they had Varta Batteries that would leak out battery acid whic in time causes trace failures and green gunk.

[Boing-ball]

But... one more issue. Some of the keys don't work. It's not random, but in vertical columns. For example the number 1 doesn't work or any of the keys beneath it (Q, A Z). Nor does 2, W, S, X. Some columns work fine though, as does the numeric keypad. Does that make sense to anyone?

That sounds like the Keyboard membrane. Might need to buy a replacement.

[Boing-ball]

The only other thing I can think of, is the Graphite of the key plunger maybe failing. You can clean these by rubbing a bit of plain paper. Either all, it will mean keyboard disassembly.