I have installed a Byrd helical cutterhead in my Jet 15" JWP-15CS. After my first hard use of it, I took out one insert to inspect the wear and edge. Today I was running the planer again. Unlike the first time, an insert broke today. I don't know if it was the insert I removed. It was on the same side of the head. But I didn't mark which one I checked.

Two questions.

1. Assuming it was the same insert, and also assuming I didn't seat it correctly, how do you tell if it is seated correctly?

2. The screw form the broken insert is trashed. It appears to be a M5-0.80x12mm flat head torx screw. I can't find any on the shelf locally. Can a hex head M5-0.80x12mm be used?