Other mechanical spares worth having
A fresh 1 1/16 inch ball reduces playfield wear. Solid state cabinets take 3 inch leg levelers. Buy rubber as a game-specific ring kit, and remember the flipper rubbers and shooter tip.
Systems
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part One, Clay Harrell (pinrepair.com)