A coil does not work in a game.

Coil-not-working checklist

Cause: If it is locked on, a failed driver transistor. If it is dead: loose wires, a broken winding, no power (fuse, broken daisy-chain link), wrong connector continuity, a failed transistor or dirty ribbon cables.

Checks

• Is it stuck on (heat, smoke, smell)? Turn off and test the driver transistor.
• Are the wires still on the lugs and is the winding intact?
• Is there power at the coil? If not, use the solenoid test Help to find its fuse.
• Do other coils sharing a wire color also fail? Suspect their shared fuse.
• Buzz the coil wires to the driver board connector and pins shown in the solenoid test.
• Test the driver transistor.

Fix

• Repair what you find.
• Reseat the driver-to-CPU ribbon cables; dirty gold contacts can stop a coil.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Grounding test for WPC coils 1-8
• No 50 V coils work
• Checking the coil supply at TP6
• One coil will not fire
• Firing each coil from the WPC solenoid test
• Why WPC coil diodes are on the driver board
• The four groups of WPC coil outputs
• One coil does nothing in the solenoid test

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Two, Clay Harrell (pinrepair.com)