Yes, I've had 2 of these so have an assortment of backs. Some better than others.
Think about what the Toast man says above. I too have noticed my advancing action can effect the spacing.
If you get too rough it can become sketchy.
I have a Rapid that cant switch backs midroll so I only need one good back.
These beasts ARE beastly but a little known gem and well worth getting the funk out of them and using them even if
they do have an eccentricity or three .