The score display for the lower (basement) playfield stays dark while the other displays work. The glass may show dark marks in its corners.

Basement (lower playfield) score display dark: wire pushed out of the A10-J6 plug

Cause: A wire had come out of the A10-J6 Molex plug that feeds that display. The connectors to the lower playfield are easily pulled apart when it is slid forward for service.

Checks

• Dark marks in the corners of the glass are normal; a white patch means the tube has lost its vacuum.
• Swap the display into the player 1 position. If it works there, the display is fine and the fault is in its wiring.
• With the display unplugged, check its harness for the high voltage (about 60 V) and the filament voltage (about 8 V).
• Check every plug between the boards and the lower playfield, including the three jacks at the back right, and look for a loose pin in A10-J6.

Fix

• Reinsert or repin the loose wire in the A10-J6 connector and make sure the lower playfield plugs are fully seated.

The display circuit carries about 60 V; keep fingers off the display pins with the game on.

Systems

• Gottlieb System 80

Games

• Haunted House

Related tips

• Displays flicker in time with the backglass light show
• All displays are dark
• Score displays are off but the status display works
• Status display is off but the score displays work
• Score displays flicker
• Score display boards by generation
• Replacing a display glass tube
• Flickering displays and erratic pops from a poor J3 ground

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