The game sits in attract mode and won't start a game; balls put back in aren't kicked into the trough.

Won't start a game: blown fuse, then trough switches not seeing all three balls

Cause: First a blown fuse (so the balls weren't kicked into the trough); then dirty trough switches, so the game didn't see all three balls.

Checks

• Check the fuses out of their holders.
• In switch test with all balls in the trough, every trough switch must show closed; the game won't start without all three.

Fix

• Replace the blown fuse, then clean the trough switch contacts (alcohol on a business card) and adjust them.

Systems

• Williams System 7

Games

• Black Knight

Related tips

• Wires to a few upper playfield lamps get hot and melt: bent lamp socket tab

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