Gauge switch health by trying the stack screws

Try tightening a few switch stack screws around the game. If most are tight the switches are probably in good shape; if they are loose, the bakelite has shrunk, gaps have moved and plenty of adjusting lies ahead. Tight stacks also keep moisture out of the bakelite.

Systems

• Electro-mechanical

Related tips

• Adjust a leaf switch at the stack
• Bend switch blades at the stack, not along the blade
• Neighbouring switches in a stack short together
• New to EMs? Do not adjust switches that work
• Why EM switch contacts get dirty
• File EM switch contacts
• Switch gap and adjustment targets
• Normally open, normally closed and make/break switches

Source: Repairing Electro-Mechanical (EM) Coin Operated Games to 1978, Part One, Clay Harrell (pinrepair.com)