My 2 XV12s started having problem traveling across my carpet because the wheels were wore down so much. At the same time I was getting occasional "clear my path" errors. Originally I did not attribute this to wheel problems, but wanted to replace them anyway. The wheels were on back order at Roboshop so I ordered 4 off e-bay. They were not original neato wheels, they were 3D printed. When I received them they looked comparable to neato wheels, only a plastic. After installing these wheels the "clear my path" error was more prevalant and at times I could hear the wheel motors turning, but no movement. Robotshop finally got the wheels in stock and I ordered 4. Both my neatos are back doing their job, without the "clear my path" error. perfect. One machine is 4 years old and the other is three.