Being involved in both hobbies, treat it like a car purchase.....inspect top to bottom, in and out. Check function of all switches, "toys", lights. If a newer game, use the test menu and run through it all. Is it clean? Playfield and underneath, wiring condition as well. If you are unsure try to find a pinhead close to you to go along (help for hauling too!) I've bought from retailers and collectors and the home hobbyist machine tends to be better.