Never used them but glad their customer service is good. Similiar thing happened to me with Muzzy's several years ago. Had one three pack of the 100 grain 3 blade heads of which the blades had play or looseness in the head, something I'd never experienced before. I sent them back in and Muzzy sent me a 6 pack back. I was more than happy.

As for the tiny allen head screws, it happens on other brands as well. Had a few screws mess up on my Rocky Mt. Turbos. I was able to secure some extra screws from a local supply store. But glad the screw threads messed up instead of on the head itself.