At the end of the game the outhole (O) relay stays pulled in and keeps the score motor running.

Score motor keeps running at game over, O relay stays in: score motor 2C switch

Cause: The outer switch of the 2C stack on the score motor was not working. That switch pulls in the match/replay relay at game over, which in turn releases the outhole relay.

Checks

• Hand-cycle the score motor and watch the 2C stack switches open and close.
• Follow the outhole relay's release path on the schematic back through the match relay to the score motor switches.

Fix

• Clean and adjust the outer 2C score motor switch so it makes reliably.

EM games run some circuits at line voltage; unplug the game before adjusting switches.

Systems

• Electro-mechanical

Games

• Hi-Diver

Related tips

• Check the score motor switches before power-up
• EM score motor will not stop
• Ball not kicked out of the outhole at game start: score motor 1D switch
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• Why the score motor home switch arcs on opening only
• Getting at score motor switches, and slowing a sequence down
• Finding a Gottlieb score motor switch from its schematic name
• What the score motor does

Source: Pinball Repair help group!! (Facebook group)