I had a similar issue so I added 4 1/32 flat nylon washers so that the there was a smooth yet tight surface that allowed the wheels to spin, Other wise the wheels were dragging and some places the belt would slip. This immediately solved my problem. If you look at the X axis it has spacers on each side if the wheels but the Y axis does not so the nylon flat washers add that. It worked for me, not smooth as glass.
Posts made by bcnyou2
RE: Y Axis stuttering while moving