The OX CNC has had some problems as it aged, with occasional problems on the Y axis.  We found this was due to the belt slipping where the original clamping mechanism cut into the belt material.  To avoid this, the Y and dual X axes have been upgraded to an adjustable and more robust clamping mechanism downloaded from Thingiverse and 3D printed on our forget-me -not 3D printer.  This makes it much easier to clamp and tension the drive belts and fixes the problem completely.

You’ll find the parts at https://www.thingiverse.com/thing:1293079 if you want to do the same for your OX CNC.