Flippers stop working, several playfield switches stop registering and the trough misbehaves. Coils fire when grounded by hand.

Flippers dead and switches flaky: bad contact on the CPU to driver ribbon

Cause: One end of the ribbon cable between the CPU board and the power driver board was making intermittent contact.

Checks

• Remove and inspect the CPU to driver board ribbon cable plugs; test each conductor end to end with a meter while flexing the plug.

Fix

• Clean or replace the ribbon cable plug (or the whole cable). The flippers returned once the faulty plug was cleaned.

Systems

• WPC Alpha-Numeric

Games

• Funhouse

Related tips

• Resets from worn power connectors between transformer, driver and CPU boards
• CPU board switch connectors
• Strange game behaviour from ribbon cables
• Replacement .100" Molex parts for the CPU switch connectors

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