Interesting, I left it on a while and it's reading in the correct range now. got close to 22 ohms for 22 ohm resistor. 6v is close as well.
Should I go ahead and replace all the electrolytic. I mean will I have problems with it in the future warming up? I'll do the isopropyl alcohol cleaning thing along with contact cleaner for switches at least. Maybe it'll be a decent meter.
It may have been noise on the power supply lines. Let it cook for a while more.
If it has been sitting off for a long time, the electrolytics can lose capacity. If they still have sufficient electrolyte, they can re-form, and potentially be fine for a long time. It likely wouldn't HURT to change them (if you do this, get good ones, not evilBay specials of unknown pedigree). I'd be inclined to let it run for a bit, then leave it off for a few days and fire it up again. If it settles in a few minutes, I'd leave it alone, parts-wise.
If you do the isopropyl clean, get it from a hardware store or HD or the like - don't user rubbing alcohol (which is
mostly isopropyl), because it usually has oils and dyes and whatnot in it - NOT something you want to put on a hi-Z board... Quite honestly, if it settles down and seems to be accurate, I wouldn't even do that - if it works, leave it be.
-Pat