switch test - make sure they all function

switch error - Even on old machines they have basic switch tests (but note some switches are pressed, like ball troughs)

Fire all the solenoids (and flashers on those circuits), make sure there are no dead transistors.

ALWAYS turn off the game, then back on again. If there's dead batteries (or worse, corroded ones), you'll get an "adjust failure". Sellers sometimes like to get the machine warm and already on when you get there, don't be fooled.

Cabinet wear is no big deal. Backglass wear isn't as big of a deal, at least if you can easily buy a replacement translite (painted glass is another beast). Playfield wear can be a big deal because it can be a pain to fix, and wear will only get worse over time with a ball rolling over it. Run your finger over the playfield, check for stickers. Often wear is covered up by stickers.