I have an old Prince battery machine that has 2 spinning wheels. The last time I used it a ball would come down the chute but wouldn't get picked up by the wheels and thrown. I cleared the ball and started the machine again. After 3 or 4 balls the same thing would happen. The balls are gamma pressureless. The machine worked fine a week ago. Changing the chute angle didn't make a difference. Is there something I need to do to scuff up the wheels so they'll pick up the balls? Or something else?