Has the gearbox seized up? Check by taking the drive belt off and turn the belt pulley by hand. It should move freely both ways. If it is ok then check inside the top panel to see if it has a capacitor. I am not sure on your model if it has one or not. If it has one then try a new one. A bad capacitor will make the motor hum loudly and not start. Does your machine have a name on the panel other than Simpson?
Lincoln Appliance NZ
September 2011