Balls locked in the couch stay there after the game ends, although the lock's coil and switch both work in test and during play.

Couch lock won't release balls at game end: it's a setting

Cause: By design. The game's default setting keeps locked balls between games so the next player can use them. A factory reset restores that default.

Checks

• Look in the feature adjustments for the setting that keeps locked balls between games (feature adjustment 35 on this owner's game).

Fix

• Change that adjustment if you want the couch to empty at game end.
• If the release still sticks, pull the release coil's plastic sleeve and clean it.

Games

• The Simpsons Pinball Party

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