I have a Kenmore dryer model maybe 20 years old? Modelnumber is 110.87880800. It has started to make a loud humming noise intermitently. It sounds like the same noise the dryer makes when it first starts. A loud vibration I think from the start switch energizing the start windings of the motor? It lasts as little as a second up to 10 seconds or so and may occur every couple of minutes.

Anyway I checked all the rollers, idler, felt seals etc. I don't see a problem It does not appear to be the gas valves/coils...as it will make the nosie when the burner is on or off with no change to the ignition.

Am I losing it or could there be something wrong with the motor or starting switch that would cause it to re-enrgize the start windings even when the motor is running. I have layed in from of the dryer with the toe panel off and watched it run, when it makes this noise there is not change in the drum speed or any signs of any drag. the motor seems to be the cause of the hum and the whole cabinet seems to be vibrating/oscillating
The motor speed does not appear to change,

Has anybody got an idea or a procedure I should try?

Thanks

Spit:)