I have a White Knight condenser tumble dryer that will not go into reverse cycle. The timer and belt have been replaced to no effect. Currently I have the top off the dryer and have to push gently on the drum for it to start turning, which runs okay until it is time for the drum to reverse, then the drum has to be pushed again. Otherwise there are no other problems with the machine which runs normally. Any ideas would be greatly appreciated. Regards.