MaxSym 400 CVT Belt Replacement

What is the good time to maintain your CVT ? 1. on MaxSym when you reach 15.000km.. mine is replaced on 17.000km.. still look good and can use further.. but need to check it regularly. 2. When you have higher RPM on certain speed, possibility roller worn out 3. Vibrations than usual. Don't forget to Greased the Drive Face Saft.... CVT Belt Roller 15Gr and U Clip 27 & 19mm Socket