The game shows a slam tilt stuck closed error at power-on and goes no further.

"Slam tilt stuck closed" at power-on

Cause: A bent slam switch on the coin door, or the second slam switch in the cabinet bottom left of the cash box, or a CPU switch input fault (ULN2803 or LM339).

Checks

• Check both slam switches.
• Game off, unplug all connectors along the bottom of the CPU board and power on: if the error goes, the fault is in the cabinet or playfield wiring; if it stays, it is on the CPU board.

Fix

• Straighten or replace the slam switch, or repair the CPU board.

Systems

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

Related tips

• Row or column "ground short" errors
• Switch matrix chips on the CPU board
• One switch does not work
• "Check Fuse F114/F115" (F106/F101 on WPC-95): step-by-step
• Lamp matrix faults with all lamp transistors good
• A dedicated (direct) switch does not work
• Switch matrix dead after a screwdriver slip under the playfield
• A whole switch column stops working: replace the ULN2803 column driver at U20

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