Y-axis belt alignment  

Y-axis belt alignment

Hi everyone!  First-time builder / poster here, and I'm having an issue with my Y-axis belt alignment.  "Step 38 - Aligning the Y-Axis Belt" doesn't work for me.  My only option for purposes of alignment is to adjust the position of the pulley on the Y-axis motor shaft.  But there does not seem to be any single location in which I can set the pulley's location to achieve alignment.  As I move the plate on the y-axis, the y-axis belt will pull left and right (measured on the x-axis) as the plate travels.  So when I loosen the screws on the pulley to align it, the pulley does not align to a single position but rather will move left and right to accommodate the movement of the belt on the x-axis.  If I tighten the screws on the pulley as the instructions direct me to do after alignment, then the pulley can no longer travel side to side to adjust as the belt tries to move side to side.  This results in increased resistance and a louder, more "rough" noise as the plate travels, presumably because of friction between the belt and pulley. 

As best I can tell, the issue is that the tensioners which fasten the belt to the plate are themselves not perfectly aligned with the idler on the x-axis, with the tensioners being relatively further away from the motor on the x-axis while the idler is relatively closer to the motor on the x-axis.  As the plate approaches the pulley, the belt position at the pulley moves closer to the alignment of the tensioners on the x-axis (i.e., away from the motor).  As the plate approaches the idler, the belt position at the pulley moves closer to the alignment of the idler on the x-axis (i.e., closer to the motor).  It seems as if I should somehow adjust BOTH the pulley AND either the idler OR the tensioners so that all three will be in alignment.  But the instructions don't provide for that and neither the idler or tensioners seem to have any play on the x-axis.   

Hopefully I've described the issue well enough, but I could post links to videos/pictures if that would help.  Any suggestions as to what I may have done wrong and/or what I can do to fix this issue, would really be appreciated!