Driver's side power window does not work, no clicking or movement when switch depressed. Other 3 windows ok. With voltohmeter, 12volts measured at motor connections inside door panel & switch changes it from 12v to 0. I removed motor connected to gear drive. When connecting leads to 12v battery ... nothing happens. Bad motor? Open rotor winding? Can I buy just the motor or rotor? What does new one cost?