LOL - I've found two dead mice underneath the plastics on my old Xenon. Complete with decomposed gore stain.
Straight up Battery acid inside a cabinet along with damage it done.
Pack of cigarettes, Roaches both insect and nefarious kind.

Found a hundo once inside coin box with a couple rolls of quarters duct taped into con box on a game I got for
free and just had to get out of a garage.

Rat droppings, garbage, soda can, snake skin. Soda that must of been 20 years old that was just a bunch of goo.
More gum that any person need ever scrape off.

This is common stuff.. Think there is a whole thread on it.

Oh yeah now what.. Vacuum it out with a shop vac. Consider yourself lucky not to have found dead mice or living ones.

The WORST thing that can happen.. TERMITES> That shit its bad news

These days most of the "Deals" are long gone and people paying to much for Pinball machines that haven't even been fully shopped, half working and not worth anything remotely what you paid.

If this was listed as Shopped, restored or something I'd raise an eyebrow but for most of us folks business as usual.

First thing I do when I get a new project or game is vacuum out the game and see what I might find inside. Usually couple fuses, tones of dust, wax residue, metallic shavings and all matter of bulbs. Once in awhile you find a part or two .

Search on Pinside bites.. Can't find the Thread on "Worst" thing you found in a game..