Specialised tools for EM switches, steppers and lamps
Have several Flex-Stone contact files and a small metal point file, 400 grit wet/dry paper (240 to 600 is usable, never coarser than 240) or green Scotch-Brite pads, a contact adjuster, a lamp socket cleaning stick, a rubber bulb remover and a pal-nut tool for holding posts. Never use steel wool anywhere in an EM; the loose fibres are a fire risk.
Systems
Source: Repairing Electro-Mechanical (EM) Coin Operated Games to 1978, Part One, Clay Harrell (pinrepair.com)