An electro-mechanical game will not start a game.

EM game will not start

Cause: A score reel not at zero (many EMs wait for all reels to reset), or sticking relays or switches.

Checks

• Check whether every score reel shows zero after pressing start.

Fix

• Clear the stuck score reel (see the score reel entry).
• As a last resort, work each relay on the cabinet floor by hand one at a time; this sometimes frees sticking contacts and starts the game.

Systems

• Electro-mechanical

Related tips

• What counts as an electro-mechanical (EM) game
• Find out if score reels are stopping the start-up
• 1970s Chicago Coin: motor runs on at reset
• Players 3 and 4 reset but players 1 and 2 never do at game start
• Score motor doesn't move to its next home position
• Score motor keeps running after start is pressed

Source: Pinball Machine Care & Maintenance, Bernard B. Kamoroff (Bell Springs Pinball Alley)