Something to keep in mind is coils don't get weak, they either work or they don't. If they get stuck on they can melt to the point the bobbin plastic can distort and cause the sleeve to be too tight on the plunger. If there's no damage like that then the issue with resetting properly can be incorrect springs, crud in the coil sleeve/on the plunger (someone tried lubing it in the past; these are meant to operate dry), or crud in the plastic sliders/on the edges of the targets (again with the lube being a problem, or old playfield wax.)

Besides the circuit breaker, another way you can prevent wasting fuses as you troubleshoot a problem is a normal household light bulb and socket. Wire it up to some alligator clips that you can hook into the fuse holder. If there's a short, the bulb will light up - instant visual indication vs. wondering if the circuit breaker has tripped.

As you can see in the attached pic, I have a 100W bulb in a porcelain base, alligator-clipped to the solenoid fuse position on the power supply. The lit up bulb is telling me there's a short...without killing fuses in the process.

Richard

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