One coil stays silent when selected in the solenoid test.

A solenoid will not fire in the solenoid test

Cause: A blown fuse, a wire fallen or cut off the coil, a winding broken off its lug, no power reaching the coil, or a bad driver-board coil diode. On WPC the coil diodes for everything except the flippers are on the driver board next to each driver transistor, not on the coil.

Checks

• Turn the game off and check every driver-board fuse.
• Look at the coil under the playfield for loose or cut wires and broken windings.
• With power on, both lugs should read 20-75 V DC to ground; only one lug live means a broken winding.

Fix

• Resolder a broken winding after sanding off its enamel, or replace the coil.
• Replace the fuse or repair wiring as found, then move on to the driver diode and transistor.

Systems

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

Related tips

• No 50 V coils work
• One coil will not fire
• A coil does nothing although its fuse is good
• One coil does nothing in the solenoid test
• No coils work at all, fuses are good
• Two or more coils fire together
• Press Start during the solenoid test for a coil's wiring details
• Coil-not-working checklist

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