The Path of Adventure mini-playfield jerks or stutters when the player steers it left and right in a game, but works normally in test mode.

Indiana Jones: Path of Adventure stutters when moved with the flipper buttons

Cause: A dirty or failing four-leg flipper button opto. Test mode does not use the flipper buttons, so the mini-playfield behaves there. If it stutters in test mode as well, the two four-leg optos on the POA board itself may be bad.

Checks

• Compare behaviour in a game and in test mode.
• Check the flipper button optos with an infrared card.

Fix

• Clean or replace the flipper button opto; if test mode also stutters, replace the two optos on the POA board.

Systems

• WPC DCS

Games

• Indiana Jones: The Pinball Adventure

Related tips

• Indiana Jones: finding which optos make the Path of Adventure stutter
• Indiana Jones: exposed switches at the Path of Adventure get bent together
• Indiana Jones: no optos work, check J905 on the Fliptronics II board
• Indiana Jones: balls keep ejecting from a crushed mini-playfield switch
• Indiana Jones: left slingshot switch touching a GI socket
• Indiana Jones: flippers die, one display line lit, balls keep launching
• Flippers, mini playfield and optos dead with endless ball search: blown 12 V fuse
• Mini playfield tilts strongly one way, weakly the other: clean and reflow its opto board

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