My 90 series Kenmore dryer stops when the start button is released. I sounds like the drum is starting to move, but doesn't appear to be. The dryer is 9 years old.

Just a quick thought, it seems like the timer has blown. The quick thing to look for is the "Door Interlock."

Normally, I am against bypassing interlocks, but it might actually help you here.

Pin the door interlock with a non conductive, like a short piece wood, small enough to manually latch the internal interlock. Next, check the interlock pin on the door to make sure it hasn't snapped off

With the door physically opened and the pin inserted, put one hand lightly on the inside of the drum. Have someone hit the start button in case you can't reach.

What you are feeling for is the amount of torque you need to use to stop the dryer drum from turning. Also, bounce the basket to see if you can p/u and flat spots on the drums supporting rollers.

If the drum stops very easily, I think real hard about either replacing the belt or have Sears replace the belt. I you hear "What I call a roundy go thump!", the idler rollers may have flat spots on them they may need to be replaced also.

Please, be advised, that while I've made repairs to this stuff over the years, I am in no way and expert. I'm just a guy with a large dead fall hammer that break anything prior to calling a pro.