Partway through a game, at no particular time, the game over relay pulls in and the flippers go dead. Afterwards the game may not serve a ball for the next game.

Game randomly ends with flippers dead: dirty slam tilt switches

Cause: The game has two normally closed slam tilt switches (one at the back of the coin door and one on the bottom board near the score motor). A dirty or poorly adjusted contact on one of them opened briefly and ended the game.

Checks

• Find both slam tilt switches with the schematic.
• Check they are closed at rest with firm contact, and watch whether a light knock opens them.

Fix

• Clean and adjust both slam tilt switches so they stay closed under normal play.

Systems

• Electro-mechanical

Games

• Quick Draw

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