John:
I use Federal 215 and Remington 9 1/2 M primers interchangeably in all the NE cartridges I load for, and find absolutely no difference in velocity or regulation. The Remington is definitely harder than the Federal, so that could be worth a try.

Regarding primer sticking, I simply round-off the striker noses and polish the tips with fine emery, although I've only had a slight problem with two doubles in the past. I wouldn't have thought this was worth sending a double across the country into a reputable gunsmith's work-queue to have fixed IMHO, although removing a stuck disc may be quite another story!

Hope it gets sorted quickly and painlessly.