So here is my quandary. I have had my "Jolly Star" grinder for close to 12 years. It still does an exceptional job. However, I was cleaning it this morning and switched it on. Not a big deal however as it spooled down I noticed the wheel appeared to be mildly out of round. As the wheel slowed to a stop I had to investigate. So I put on another (brand new still in the plastic the pink ones from Bailees) So now I switched the grinder on and still had the same problem. I have never noticed this before. I removed the collar that centers the wheel and it appears fine. So now I am wondering if the armature on the motor could be out of true. Could this be possible? When grinding chains there is virtually know vibration however, as the wheel eventually slows I am able to feel the vibration in my hands. Any free words of wisdom are gladly appreciated. Thanks, Ken