I've had a devil of a time with my 550B primer slide. I cleaned it and lubed it, and still it would stick. I bought a second one, and STILL it would stick.
I finally decided that the predominant reason for the sticking is the fact that the actuating rod sits so far off center from the slide that it wants to cock in the primer tube raceway as it moves to the rear, and that makes it stick. Accordingly, I bent the bottom leg of the actuating rod to the left, so that as the slide moves back the actuating rod and roller moves inwards more towards the slide itself.
And that finally fixed it.
-A conclusion is not a destination, it's simply a convenient place to stop thinking.-
-Reading a thing doesn't automatically make it so; repeating it doesn't necessarily make it any truer.-
-Every Texan should be a member of the Texas State Rifle Association.