The trouble usually lies in the X/Y saddle itself, and/or the X-ways. If you can get a Machine straight edge, (borrow or beg), and lay it up againts the x-ways, and then check the X saddle ways, you might find your problem.
I had a simular problem as you described when I initally got the machine (sometimes the castings are bad and slip through the questionably QC at the china plant). If you machine is still under warrenty, you can get John to replace the X axis way, and/or Saddle if one or the other or both is off. For me, I hired a guy who does machine ways, and had him scrap/fix mine ran me about $200.00... But they are smooth now.
A "poor mans" way of cheaking the quality of your ways/saddle is tighten up your X axis way till you get a slight drag on the saddle around the middle of the machine, then move it right and left all the way to the endes of travel, "Feel" the X axis while you slowly turn it. If you feel it "bind" here and there then you know the fit is bad.
scott |