AVRC wrote:The nut does look crooked, but the bolt appears in too good condition for it to have been cross threaded.
Can you post a another picture or two, directly from the side, centered on the mounting plate?
It does rub lightly against the idler holder bracket with all screws and nuts installed properly. It looks like the belt clamp step, which gives the belt a guard distance from the gantry plate, is 0.5mm too high. Here are some photos:
One can see the back of the belt as it leaves the belt clamp at the left and the socket screw head rubbing against it, at the center just below the V-wheel. The other part of the belt ( the one with the teeth ) is closer to the plate but still at a safe distance. This happens only when the gantry is close to the idler bracket. At some distance from it, the belt clears the screw head and the distance increases as it goes to the motor side.
The belt in the photos is installed all the way into the clamp jaws and held securely there. A washer between the pulley and the plate will most probably solve this issue.