F8 is on the PPB. It drives the high voltage coils if memory serves me correctly. The burning smell was probably the wrapper around the coil melting.
Do you have a good multi meter that can read ohms?
Does it have a diode setting?
You will need to figure out which coil locked on. Replace the melted fuse. Take the glass off and raise the playfield. Turn on the machine briefly and try to spot the coil that fires and stays on. If you cannot find it in a couple of seconds turn the machine off and let the coil and the fuse cool for a few minutes and try again.
Once you find the coil take the wires off the lugs. Put the multi meter on ohms and put connect one end to each lug. It should be above 4 ohms. If it is replace the diode on the coil, pay attention to which way the band is. Put the wires back on as they were.
Now you need to pull the popcorn popper board. Look in your manual for the coil chart. It will tell you what transistor drives that coil.You need to replace the large tip36c (someone correct me if I am wrong its been awhile) with a new one. Put the PBB board back in and pull the driverboard. Look in the manual again to figure out what transistor drives that coil. It should be a tip102 or tip122. Replace that one with a tip102 and its predriver if it has one.
That *should* fix the locked on coil problem.
Have you replaced the broken fuse clip? If not make sure you replace both ends at the same time as they tend to fail one after the other. I would go around and check the other fuses. Firmly press down on each fuse. If the holder gives way it needs to be replaced.