Whatever you do, don't toss that Firepower PROM. Send it to me and I will solder the legs back on and send it back to you, no charge. Or if you decide to go combo ROM, I'll just put them in my backlog of Firepower parts.

I use twin leaf sockets too. I find they are easier to install these fragile chips than the machine pin sockets. I don't use cheap Chinese sockets but rather brand name sockets from reputable parts houses. Never a problem here....

It sounds like your flipper coil is bad but I doubt the flipper diode is bad. The .6 is a guideline and .572 is close enough. A bad diode will read 0 or infinite, not something so close to .6. That being said, your new coil will come with a new diode anyway...

On the flipper transistor, you mention that the solenoid fuse constantly blows, does the flipper fuse blow? Do the flippers work when you start a game? The flipper circuit on FP is quite simple. Q13 simply turns the relay on and off providing power to the flipper coils. If power is getting to the flippers when a game is started, there is nothing wrong with Q13 or D1. You didn't mention that you are having troubles with the flippers in your post so I'm not sure why you are suspecting these parts...

On the solenoid fuse, did you test all the solenoid transistors? Did you test the resistance of the PF solenoid coils? Check the electrolytic capacitors on the sling stitches and pop bumpers to see if they failed shorted (common) which would cause these coils to lock on when a game starts.

Does the solenoid fuse blow when you start a game or when you turn the game on?

On the pop and sling caps, if they read zero, they are shorted and should be replaced... No need to have the boards installed to test this...

If you are getting power on one flipper, you can stop looking at the transistor and the flipper relay as both flippers are powered by the same relay. You either have a coil problem, EOS switch problem, flipper switch problem or wiring problem on the suspect side. Try holding the flipper button on and manually moving the flipper up and see if it holds up. If it does, you may have an EOS or power coil problem. You can also try measuring the voltage across the flipper switch while in a game.

That burnt resistor is the warming resistor for the FIRE and POWER flasher bulbs in the hotdog inserts. It being burnt would not cause the solenoid fuse to blow but will cause your flasher not to work properly. However, if you are planning on using LED flashers, you should just remove it as it will prevent LED flashers from working properly.

If you wish to stick with regular #89 flashers, replace it with a 330 ohm 2 watt or bigger wattage. The smaller resistor is a 1 ohm, 1/2 watt. The 330 ohm resistor is commonly fried on Firepower machines unless someone before you replaced it with a larger wattage resistor (does not appear to be your case).

The circuit for the flashers is on page 25 of the Firepower schematics. Look for the 2 flasher bulbs on the center right of the page.

For item 1, check that the switch stack below the pop is setup like the others. One of the blade can get our of position and the energized coil can keep the switch closed. If the switch stack is ok, can you tell if the coil is locking on or is it a mechanical problem preventing the spring from popping it back up?

For number 3, did you have 3 balls in the trough? The firmware will not start a game unless all3 balls are detected. If there were 3 balls, check the trough switches for proper operation (may need to be cleaned).

Yea, they are 22uf and 100v will work but you really don't have to go that high in voltage rating.

Also, Mouser looks to be crazy expensive on that capacitor. Not sure what Ed charges for shipping up north but he sells them for $.25 US...

https://www.greatplainselectronics.com/proddetail.asp?prod=CEA-22uF-50V-RMD

Wouldn't be a bad idea to stock up on several and some spare transistor, connectors and such. He also has great deals on capacitor kits for the Williams System 6 sound board, power supply rebuild kits. Pick up some 100uf/25V caps for the filter on the driver and CPU boards.

Awesome job, congrats! Feels great to fix it yourself, right?

Ahhhh, the flipped one way gate.... been there many times myself! Happens when testing with the apron off, the ball will flip the wire gate over the top and if you don't see it and flip it back over before putting the apron back on, it becomes a block. Nice catch and thanks for posting the resolution to remind us all!