Quote from Reloader on July 13, 2015, 8:35 pm

I was having some problems with my 550 and got real frustrated. I remembered a similar problem several years ago and checked the roller bracket shell platform. Sure enough it was loose. It is very difficult to tighten, but it solved my problem. We are back on track and priming just fine. This might be something you want to check if you are having priming problems.