Are you saying that the motor runs but there is no brush rotation ?
If yes then firstly switch machine on then when you pull handle back as if to vacuum the carpet the clutch drive dial must turn to (drive, start, on,) position if it is stuck on (park, off. Stop, p,) position rotate it to drive etc as you pull handle back providing the clutch & both drive belts are ok the brush will spin.
The clutch drive dial knob is situated looking from the front of machine lower left hand side approx 50mm or 2” in diameter.
Please do this test & let me know results