Something blows the underplayfield fuse. When doing the test mode, the 14th solenoid doesn't fire, and the fuse blows after solenoid 17 fires.
The manual says the 14th is the drop target n°6, but it's solenoid fires correctly in 13th position.
It seems the loop drop target (firing in 17th position when in test mode, while the manual says 18th) will also blow the fuse when activating in game.
Both solenoid have correct resistance when tested.
While in game, and when the ball goes in the lock area and all targets are dropped in sequence, the target 6 will sometimes drop with its solenoid firing repeatedly, freezing the game but not blowing the fuse. The fuse will then blow when restarting the game. I don't know what to make of it.
Edit : See later post for an update.