There are 18 solenoids in this game that are controlled by 3 connectors 1J-11, 1J12 and 1J-19. Disconnect all 3 connectors and replace the blown fuse, then turn on game. Then take an ohm meter and check the resistance from ground to the metal tabs of the larger drive transistors. Which transistor reads low ohms?

The metal tab on the larger transistors is the same as the collector lead. Its very safe to check to the metal tab with the power on. Now the reason I suggest to have the power on is because there can be other issues that can turn on a good transistor that can't be found with power off. Your method of diode checking transistors with the board out of the machine is fine, and will most of the time find a bad transistor. But if the transistor is good and there is a broken trace or an open resistor in the circuit it can turn on the transistor locking on the coil and burning the fuse. I use resistance to check this with the red lead to ground and test with the black lead on the transistor tab, a reading of @ 2 meg ohms is average for a good part and something @ 3k ohms and lower for a bad transistor.

TIP100_PKG (resized).png

You don't need the coin lock out coil in a home environment.