On both my 550b's, I have this recurring problem where the Primer Slide does not want to go all the way in to the Primer Housing to pickup a fresh primer on the DOWN stroke. However, a slight nudge on the Primer slide would make it go in. I've checked all the alignment by following the manual and they seem to be correct. Looking at it closely, it looks like the Primer Seating cup occasionally hits the side walls of the primer housing on the way in.
This had become annoying and really disrupts my reloading process as I have to always check and make sure that the slide always goes all the way in.
Any suggestions?