If you have just brought the Rotor, it could be as simple as you have not put the floor tray back in properly, ( the bit in the middle of the hopper which the balls sit on) Make sure it is under the tabs at the front AND you have clicked it in place at the back.
If it has suddenly started misbehaving then take everything a part and reinstall slowly. I had this happen and found the small screw on on the centre rotor arm was loose and tightened that down (hand tight...always hand tight for everything paintball
), and all worked again.... so could have been that or just the reinstall that worked.
Rotors dont like old or mishaped paint and will jam....as I found out last training session.