The pulleys for the X axis don’t move at all when there is only movement on the Y-axis. For X-axis 2 belts roll tooth-side on smooth and two are smooth on smooth. I tried adding some tape to the smooth side ones and there was literally no change. I stopped at 6 or 7 wraps of various lengths (to avoid overlapping the same spot too many times) and even at the last additional wrap I saw a subtle improvement. I haven’t wanted to chase the upper limit because there will be a point where too much tape causes new issues, and removing the tape is very tedious.
Yeah, the belt is GT2 - I 3D printed a GT2 pulley for one of the motors and bought a permanent metal one and the fit is perfect. I am curious about your idea!