This is a food processor that has never been used. The motor will not turn on when turning the knob to the proper position. The only way the motor will turn on is if we take a long stick and reach into the skinny motor opening to manually push a white tab from left to right and hold it there conintuously for the motor to run. What might be the problem? Thank you so much for any advice and expertise you may have

Lynda, January 2010