A pop bumper still scores and makes its sound when hit, but the coil never fires, in play or in solenoid test. Repinning the board connectors and swapping the solenoid driver board made no difference.

One pop bumper scores but never fires: broken wire hidden under shrink tubing at the coil

Cause: A wire had broken off right at the coil lug, inside heat-shrink tubing that hid the break.

Checks

• Check for coil voltage at the coil, and ground the tab of the driver transistor for that coil (use the transistor map for the game) to see if the coil fires.
• Slide back or remove any shrink tubing on the coil lugs and inspect the wire ends; also check the coil's power (common) wire, which may be daisy-chained from a neighbouring coil.

Fix

• Resolder the broken wire to the coil lug and re-insulate it.

Coil voltage is present at the lugs with the game on; power off before working on the wiring.

Systems

• Bally MPU AS-2518-35

Games

• Eight Ball Deluxe (LE)

Related tips

• LE: one coil fires another (outhole fires a memory coil): coil diodes
• Most coils suddenly dead, flippers fine: broken power wire on a pop bumper coil lug
• Top lane gate never opens, even in solenoid test: failed driver transistor
• Wrong coil fires or a coil never fires
• Use the solenoid test to find a coil that does not fire
• No coils work at all
• Solenoids fire out of order in solenoid test
• Coils go weak or the wrong coil fires mid-game: reseat the solenoid driver plugs

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