Yes, very worthwhile topic. One thing when doing a playfield swap (especially repros), and maybe even when changing the base plate. Often these are dimpled for the screw holes on repros. My advice is to ignore the dimples, and instal the bush/flipper base and make your own marks for holes because if the placement is off, the bush can end up forced along one side, and slightly warped. This was enough to give me problems with a Funhouse swap a few years back, took a while to diagnose.

Good point i dunno if i have the same problem with my fh swap but will look out for this in the future. I may have ignored the dimples because my flippers seem ok i think