As usual, Lloyd is most likely correct here. There is a smaller guage purple wire with a green stripe that goes from the aux driver board in the head all the way down to the 4 coils that are controlled. This wire is critical to protecting those drive transistors from getting fried by the coil flyback. That wire easily breaks. Once it does, any of the 4 coils on that side of the driver board (if memory serves it's both subway diverters and the up/down of the drop target), once fired, can blow or weaken the 4 drive transistors. My money says that both diverter coils are locked on and only one has completely melted down so far. And yes, this happened to me.
First thing, find that wire... it goes to the 4 diodes on the aux driver board. It's a horrible design choice they made to wire it all the way down to the playfield when the clamp voltage is already available in the head. Find it and make sure it's still connected to the coil down below. My bet is that it isn't. If it's broke, there might only be 2 transistors fried, but all 4 are weakened. I replaced all 4 just because I didn't want to have to fix it again later. Then replace the coils that are damaged. For sure one subway diverted, probably the other as well. The drop target coil is probably ok.
Best of luck!
Jaz
Post edited by Jazman : Clarity