The upper right flipper comes up on its own at the start of a game and in test, even with different CPU and Fliptronic boards fitted.

Upper flipper energises by itself: shifted magnet on a magnetic button board

Cause: The game had an aftermarket flipper button board that senses the button with a magnet. The magnet actuator had shifted off centre, so the board reported the button as pressed.

Checks

• Unplug the cabinet button board; if the flipper still fires, look at the Fliptronic board.
• On a magnetic-sensor button board, check the magnet sits centred over its sensor.

Fix

• Re-centre and secure the magnet actuator on the button board.

Systems

• WPC Fliptronics

Games

• Twilight Zone

Related tips

• Upper flipper weak, then dead: blown fuse on the Fliptronic board
• Games that came with Type 1 flipper opto boards
• WPC flipper coils from weakest to strongest
• Flipper coil strength order (WPC flipper coil strengths file)
• Upper flipper button wired but not used on some games
• WPC-89 resets on low +5 V: replace the small 100 uF 5 V filter caps
• Fliptronic flipper dead: check the button first
• Flipper energises at power-on (Fliptronic)

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