The game resets soon after launching a ball and sometimes won't start at all.

Game keeps resetting during play: poor J101/J102 power connections

Cause: Poor connections at the power driver board's J101 and J102 power connectors (the female plugs had been replaced but not the male header pins), plus loose ground screws.

Checks

• Tighten the board grounding screws and reseat J101, J102 and the ribbon between the power driver and CPU boards.
• Measure 5 V at the CPU (about 4.95 V or more is normal) while the game runs.
• If reseating helps only for a while, the header pins are worn.

Fix

• Reseat the connectors as a first step, then replace the J101/J102 header pins and repin the plugs for a lasting fix.

Systems

• WPC Alpha-Numeric

Games

• Funhouse

Related tips

• Resets: +5 V at the driver board test point is low
• Pre-WPC-95 resets: replace BR2, C5, C4 and the J101 pins together
• Funhouse: flipper buttons won't step through high score initials
• What a WPC game reset is
• Watching the supplies while the game resets
• WPC CPU board LEDs at power-on
• Raising the WPC/WPC-S +5 V to about 5.15 V (last-resort reset fix)
• Resets remain after rectifiers, caps and connectors are done

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