Cannons (STNG, Terminator 2) or other moving toys such as the Medieval Madness trolls work on and off, or keep moving at power-on.

Cannons or moving toys work intermittently or won't stop

Cause: Constant flexing breaks wire strands inside the insulation, usually at a cable tie or sharp bend, where it can't be seen.

Checks

• Check the moving wiring for continuity while flexing it (this doesn't always find the break).

Fix

• Replace the wiring loom; on STNG the cannon looms are a high wear part and should simply be replaced.

Systems

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

Games

• Star Trek: The Next Generation
• Terminator 2: Judgment Day

Related tips

• Cannon fires late or drops its ball: cannons bent downward
• Cannon often won't fire during play: adjust the at-mark switch
• Cannons and a flipper lose power at once: a fuse that looked fine was blown
• Sound board fuse F501 blows at power-on (A-12738)

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