We've seen a few machines that seem to be slipping or shifting in the X and Y axis. The pulleys don't seem to be loose, but replacing the bearing holders seemed to fix it. It seems that a lot of them are too tight to begin with before installing it on the machine, then it gets worse on most of them once you tighten them down.
@gregh The new bushings in hibiscus are higher precision bushings so they have tighter tolerances on the rods. If the bearing holders aren't reamed out well or if two sets of bearings aren't aligned well, then there will be bushing drag in that axis. Since you mentioned it seems too tight before installing on the machine i would suspect that there was a reaming issue with those double bearing parts.
@kent do you think there is any way we can improve reaming on the double bearing holders?