Off and on, for month now, I have had some issues with the bar, which picks up the primer from the primer tube. On the return trip to place the primer, the bar "chatters" sometimes and hangs up. I take care to clean that area (blow air to clean it out), and use moly dry lube on the moving parts, especially the primer bar bearing plate. That's the black plate that sits under the sliding aluminum bar.
I've tried all sorts of things to elmininate the chatter and hang ups. I finally hit on a solution, and hope that it might help others with a 550b. It might even work on the 650 XL's.
The return spring for the bar clips onto a vertical pin/rod. The top end of the pin/rod stops against the head of a hex screw. The lower end of the pin/rod has a groove machined out to hold onto the loop at the end of the spring.
That pin/rod is a press fit in the hole that it's in. I tapped the pin UPWARDS a smidge, such that the spring is up against the bottom of the plate assembly, but not touching. It was MUCH lower before I tapped it up. Now, the returning bar is being pulled almost exactly along the same plane as the bar, and returns perfectly!
Out of focus picture, but hope that you get the idea:
I've tried all sorts of things to elmininate the chatter and hang ups. I finally hit on a solution, and hope that it might help others with a 550b. It might even work on the 650 XL's.
The return spring for the bar clips onto a vertical pin/rod. The top end of the pin/rod stops against the head of a hex screw. The lower end of the pin/rod has a groove machined out to hold onto the loop at the end of the spring.
That pin/rod is a press fit in the hole that it's in. I tapped the pin UPWARDS a smidge, such that the spring is up against the bottom of the plate assembly, but not touching. It was MUCH lower before I tapped it up. Now, the returning bar is being pulled almost exactly along the same plane as the bar, and returns perfectly!
Out of focus picture, but hope that you get the idea: