There have been reports of the x-axis belt getting worn by the x-axis idler pulley on Prusa i3 MK2S printers. Happened to me. Looked for a decent solution but didn't see one. So I remixed the Prusa x-axis idler.
I wanted something that would work without purchasing any weird metric nuts and bolts cause there aren't any decent hardware stores where I live. Luckily Prusa ships a box of spare parts, including two long bolts and two self-locking nuts. So I used them to create what you see. By slowly adjusting the bolts in and out you can shift the x-axis idler pulley just enough to reduce or eliminate that black dust that used to be your belt.
I printed mine in white ABS just to be sure to see any dust. So far, so clean. The PrusaSlicer file (.3mf) is, however, set to orange Prusament PETG and has a support enforcer box.
The author remixed this model.
Made one end of the axle adjustable