Since 2025, Prusa has been using washers as spacers for the Prusa XL pulleys. No more O-rings.

You can buy the new washers form Prusa here: https://www.prusa3d.com/de/produkt/washer-3x7x1/

I’ve already written an article about the new 2024 O-rings. You can find it here: https://investegate.de/prusa-xl-new-o-rings/

Prusa has published newly adapted CoreXY parts on Printables.com for the new O-Rings. These parts also fit for the new washers!

It is recommended that you reprint the modified parts during your next extensive printer maintenance and integrate them together with the new Washers. You can also maintain or, if necessary, replace the idler pulleys at the same time.

You may have noticed that there are two idler pulleys in the X-carriage, where the toothed side of the belt is guided over smooth idler pulleys. Why Prusa doesn’t use toothed idler pulleys for this is a mystery to many. This can cause the belt to deform. Therefore, it is recommended to use toothed idler pulleys. All parts and information can be found here: https://www.printables.com/model/1135912-prusa-xl-modified-corexy-parts-for-new-o-rings-wit