I have a TS2424 that has always passed the nickel test without fail, that is until recently. The saw has developed a vibration only during startup and shutdown. Once the saw is up to speed, a nickel will sit there all day long. There is an initial jerk when I start the saw but then smooths out. When I shut it down it is smooth through most of the shutdown, but then as it slows it start vibrating and you can see the motor bounce. I pulled the belt and checked the pully alignment a few weeks ago and they were aligned. The interestinng thing was that after I put the belt back on the vibration went away, but came back after a few days. I have not been able to determine the cause. I kind of suspect maybe a set to the belt, but I had read many times here and elsewhere that this type belt will not take a set. Does anyone have any suggestions what else to look at to isolate the source of the vibration.