Z Axis belt not tracking well

[drew]

I'm having a problem where the belt on my Z axis crawls from one edge of the drive and idler pulleys depending on the direction of rotation. Once the belt gets to the edge the stepper stalls.
Another interesting thing is that after the stepper stalls it's rather indeterminate which way the stepper will spin regardless of the DIR line.

I've tried different amounts of tension on the belt along with flipping it over and so far nothing seems to make a difference.

I would normally think this would be an alignment issue with the pulleys but I'm not sure what could be done about that.

Thanks for any advice,

Drew

[mhackney]

Check the idler - it might be canted and causing the belt to move. The stock idler is tricky to adjust so it is both tight and still allows the idler to spin freely.

Cheers,
Michael