I just got my very first pin - a SS Joker Poker! It's about 90% working and I'm trying to learn as I go. When the machine is turned on, the 1A fuse which controls the 10/Jack coil blows after about 3 seconds. I've tested the coil (9ohms) and the diode and both were good. Then I just went ahead and replaced them with brand new components and it still blew. Sounds to me like there's a short somewhere. Yet, this part of the machine is stupid simple and I can't figure out where the problem is.

There is 24V coming from the 24V rail (which powers the other coils/fuses just fine) going to the 10/J coil lug. Then there's a wire going from the other coil lug to the driver board. And that's it. Nowhere do I see any of these 2 wires touching anything they are not supposed to.

Some basic game info:
- Brand new boards (power/CPU/driver)
- Made the ground mods on the power/driver boards (can't figure out how to do it on the CPU since it's new and doesn't have the capacitor that all of the sites reference)
- Other drop target coils working (powered from the same 24V rail)

Any help would be really appreciated for this newb...

Q31 tests bad on the new board (and it's right above Sol. 6), so I'm guessing that's my problem. Alright, I have a path now. I'll get a replacement transistor, solder it on, and report back. Thanks!

Replaced the transistor and it's working now! Thanks @inkochnito!