Quoted from vec-tor:
Evolution of Bally's later flipper coil stop hardware:
Some are self tapping...
All basically are 3/8th of an inch long
All are 10-32 thread.
Best practice is the last piece on the far right; used by Williams.
I have seen 2 variations of the linear flipper mounting plate. 8-32 and 10-32 for the coil stop. The 10-32 mostly on the 84 games, like the last version of EBD and Spy Hunter etc. Therefore one must have the coil stops with the larger holes to accommodate the 10-32 screw.
Like I posted earlier in this thread and most people don't realize, these mounting plates are reversible so if the screw holes for the coil stop are wiped out you just flip the bases to the opposite sides. There are usually virgin holes so all the parts can be transferred to the new holes without having to drill or tap them. You just thread a self tapping screw in the unused holes. You need to make sure the screw threads are in good condition, use one from the bushing or EOS mounting bracket. The screw will be snug as it goes in, and it can be backed out a little to let metal shavings fall and then thread screw down until it bottoms out. Remove screw and you have a nice clean threaded hole to work with.