Sound plays, but nothing at all comes from the right backbox speaker, even with a known good speaker fitted and new connectors at the sound board.

Right backbox speaker silent while the left works: failed tweeter capacitor

Cause: The right backbox speaker is a tweeter fed through a small non-polarized capacitor that filters out the low frequencies. That capacitor had failed open.

Checks

• Check the wiring: the two backbox speakers are connected together, with the capacitor in line to the tweeter.
• Bridge in or swap a capacitor of the same value from another game to test.

Fix

• Replace the non-polarized capacitor on the tweeter with one of the same value.

Systems

• WPC Fliptronics

Games

• The Addams Family

Related tips

• Pre-DCS sound boards are tuned per game
• No audio output at all from the sound board
• Random stray sounds in attract mode after changing the CPU board
• WPC-89 sound board: digital volume control does nothing: broken trace at the X9503

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