We have an Ultimaker Original+ that has a tendency to jam, because the plastic part of the delrin wheel shifts sideways on the metal bearing until it's pressed up against the wall, and no longer turns. This causes underextrusion or even for the print to fail entirely. There is no real pattern to how often this happens, sometimes it'll print fine for ages and sometimes it will go wrong three times in a row. It's easy to push the plastic wheel back into the centre so it turns again, but I would really rather it just stays there. Other than replacing the delrin wheel, is there anything I can do to stop this happening?