The buttons work the flippers but not the video mode or high-score entry.

Flippers play fine but buttons do nothing in video mode or initials entry

Cause: Each flipper opto board has two U-shaped optos; on two- and three-flipper games the second one is used for video mode and initials. It is dirty or bad, or the activator does not clear it.

Checks

• Check the second opto on each board and the activator clearance.

Fix

• Clean or replace that opto, or fix the activator.

Systems

• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Fliptronics: flipper button does not register in switch test
• Fliptronics: flipper coil gets hot after a while of play
• Fliptronics flipper does not work: test the flipper opto board
• Fliptronics: flipper will not hold up (flutters)
• Flipper gets weaker the longer the game is on
• One flipper dead and its button fails switch test: dirty flipper button opto board
• Upper flipper sometimes weak, then buttons dead after cleaning: replace the flipper optos
• Fliptronics and WPC-95: weak flipper

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