If the slingshot switch was adjusted too close together then it could lock the coil on, thus blowing the fuse that drives all the "special solenoids" (slingshots, pop bumpers). Of course, it could be a blown transistor for that slingshot, as well. Check the coil to see if its burnt/melted, and confirm with a multimeter that it matches the resistance of the other slingshot coil. If its down below 2.5 ohms or so, its probably shorted and needs replaced. Coils don't just go bad, though.... there's something that caused it to get cooked like a bad transistor or a stuck-switch. Williams didn't upgrade that switch circuit until about a year later so stuck switches wouldn't fry coils.
Check the switch, check the coils, then check the transistor and see what you've got.