Hi @dlang , thanks for a speedy response. Maybe some more detail will paint a clearer picture.
The sled is cantilevering, meaning the bottom (where dust collection exit port is typically installed) elevates off of the work piece by about 1cm.
It only does this at the left most edge of the work piece, whilst moving upward.
Here the primary contributor to travel is the top left belt. This belt has the highest installed height.
Due to the belt install height, the lack of tension on the opposing belt, high center of gravity of the machine, and friction of the work surface, the sled visibly cantilevers whilst traveling upwards in y.
The linear rods are not flexing when lead screws are not turning, but could if the z motors were to stall. The top z motor therefore obligingly stalls with the default drive current when the machine tries to cut 45 degree angled support tabs whilst moving up on the y axis.
This is the issue. I have taken steps to independently prevent cantilevering and motor stall. With these steps combined I have been able to work around the issue so far.
The belt is not hitting dust collection.