If the focuser runs out of round, or drags, or jams...

Product Description
If the focuser is running unevenly, dragging, or wobbling, or the focus knob is spinning, or the 1:10 reduction gear is rattling, the knob is often loose, either on the 1:10 automatic or on the shaft.

If the 1:10 reduction gear is dragging, you can move the knob outward a little. Less than a millimeter is enough.

The photos show where the grub screws are usually located. To do this, you have to turn the shaft until the screws appear below the opening.