Quoted from Leosac:

Help please!! Multiple symptoms....
Upon game start up the solenoid that loads the ball up to the ball shooter won’t fire.
It had seized up and actually melted the sleeve. I replaced the coil, it repeatedly fired for a bit but the balls wouldn’t load. Heard something pop in the backbox. Not sure if it was related or not. Now the solenoid doesn’t fire at all.
I know that description is all over the place, any ideas to help me focus the trouble shooting.