Four coils from two different groups (gumball diverter, gumball popper, left and lower jet bumpers) do nothing in solenoid test, though they have power and fire when their drive is grounded.

Gumball diverter, popper and two bumpers dead in test: faulty CPU ribbon

Cause: A faulty ribbon cable between the CPU board and the power driver board was not passing the drive signals.

Checks

• Confirm the coils have power and fire when grounded, so the coils and their wiring are good.
• Reseat both ends of the CPU to driver board ribbon and retest in solenoid test.

Fix

• Replace the ribbon cable between the CPU and driver boards.

Systems

• WPC Fliptronics

Games

• Twilight Zone

Related tips

• Burned power driver board traces at the header feeding AC to the Fliptronic board
• Outhole, shooter diverter and gumball motor all dead: CPU board chip at U4
• Lower pop locks on at power-up: J124 plug fitted on J128
• DMD dead though display and controller work in other games: CPU board fault
• Left mini-playfield magnet dead, about 8 V at it: F101 blows, shorted Q26
• Resets from worn power connectors between transformer, driver and CPU boards
• Resets during the Powerball battle: reseat J101 and J115 on the power driver
• GI string dead with a scorched connector

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