The roller (grinding head) lasts for a few sessions depending on frequency of use and size of the area being treated.
Make sure the unit is turned off before replacing the roller grinding head.
1. One hand holds the head, and another hand presses on the release button (on the side of the unit), and the head will come out.
2. Simply place a new roller (grinding head) into the unit until you hear a "click" sound. Be sure to insert the new head into the unit, and do not turn on your unit if the roller grinding head is not securely attached.
3. Check the unit to ensure the roller is securely installed.