My bosch dryer is making a new noise. It is intermittant and varies in how loud it becomes. As the drum rotates there is a corresponding "howl" or harmonic if you will, that can be very soft or increase in noise level to the point it can be heard all over the house. It doesn't happen with every load but with most. Usually the drum rotates a few times before the noise starts. If I open the dryer and push the drum a bit it will change the level of the sound but does not irradicate the noise completely. The service man is coming today and I am wondering if you have any suggestions that might assist me in dealing with resolving the problem. The dryer is under extended warrentee.