1. Loose the side knob (B1) and open the side cover (B2).
2. Use a 4mm kexagon wernch to loose the screw (B3), unscrew it counter-clockwise.
3. Replace with a new diamond grinding wheel and tighten
the screw after the wheel is installed.
4. Be sure to close the side cover (B2) properly and to
fasten the side knob (B1).