How can I fix my Servis m2010 tumble dryer?

When I operate the push button switch the dryer rotates but stops when I release the switch. When holding the switch in manually, the machine stops when I either open the door or the timer reaches the off position. Holding the push button switch in manually, the machine rotates and reverses as normal and the heater works. Is it possible that the push button switch is faulty and won't lock in or is it probably something else?