Hammer wants for 6 Kunsstoffrollen under the seat (diameter 4 and 6 cm), which are characterized already in the prospectus as wearing parts and are just crumbles us here 70 plus. Those are also truly the most expensive items on the device. ;-) In the customer service (we should throw away our no longer functional unit now and buy a new, or what?) I can only recommend to buy other brands !!! If it was not would be so sad, can almost laugh ma.