Random multiball at any time, drained balls not seen, the game won't start, or the game never ends because it thinks balls are still out.

Random multiball or game never ends on early opto troughs

Cause: On Indiana Jones, STNG, Judge Dredd, Popeye and Demolition Man the trough opto boards were bolted straight to the trough. Vibration breaks the leads of the large blue 2 watt resistors and the transmitter LEDs.

Checks

• Look for broken leads where the blue resistors and LEDs meet the board.
• Run the trough tests in switch edge test (see the trough opto test procedure).

Fix

• Replace broken resistors (270 ohm 2 W) and LEDs.
• Remount the boards on rubber grommets with metal bushings, or fit the A-18244 upgrade kit.

Systems

• WPC DCS

Games

• Indiana Jones: The Pinball Adventure
• Judge Dredd
• Popeye Saves the Earth
• Star Trek: The Next Generation

Related tips

• Remounting early trough opto boards on grommets
• Random multiball from cracked blue resistors on trough boards
• Balls hang in the trough: divots in the trough metal
• Turn ends while a ball is still in play in Final Frontier: flaky trough opto
• Opto ball troughs from Indiana Jones on
• Full ball trough opto test in switch edge test
• STNG random multiball after the trough upgrades
• All playfield optos dead after replacing one opto: failed 16-opto board

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