When a new game starts the score motor keeps running.

1970s Chicago Coin: motor runs on at reset

Cause: 1970s Chicago Coin reels sense zero only through stepper-style wipers on a bakelite board; if the zero wipers do not touch, the game never sees zero.

Checks

• Check the wiper fingers press on the board and the board is clean.

Fix

• Clean the board and wipers and set the finger tension.

Systems

• Electro-mechanical

Related tips

• Players 3 and 4 reset but players 1 and 2 never do at game start
• Score motor keeps running after start is pressed
• Score motor runs on and the game never starts
• EM score reel will not reset to zero
• How the score motor resets the reels
• EM score motor will not stop
• Score motor runs on at start, a reel locks on: mis-gapped reel switches and solder
• Clean Chicago Coin plastic score reels only with Novus 2

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