Are you sure your pen is not just loose in the holder? What surface is under the paper? A pen is a poor tool to try this test with unless it is spring loaded. The one in my video is a spring loaded liyu pen, made for this kind of thing.
I would say strap a cutter on it and make a test cut in some high density foam.
Don’t worry about the conduit, it is smooth enough, promise.
The belts and steppers should provide enough drag to where you can’t feel anything anyways, unless you take the belts off.