The game will not end and go back to attract mode.

Game never returns to game over

Cause: The outhole switch is not registering: broken wires, its diode, its LM339 or U20.

Checks

• Test the outhole switch and its wires.
• Check its diode, then the comparator and U20.

Fix

• Repair the switch circuit or replace the failed chip.

Systems

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

Related tips

• Random multiball or game never ends on early opto troughs

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