I have a Dewalt 421 orbital sander and I'm not sure if it's working properly. Holding it off the work, I turn it on and the orbital function seems fine, but the rotating of the sanding disk is my concern. When held in the air, the sanding pad spins a quite a high rpm and if the sander is not placed on the work perfectly flat, a gouge will occur. Once the sander is on the work, the rotation of the pad slows way down where it is barely rotating, but the orbital part is orbiting away. I don't remember if this is how it always worked or if the rotator clutch (???) is slipping. Are you supposed to turn the sander on with the pad in contact with the work to avoid the gouges that can occur from the high speed spinning pad. Your help is greatly appreciated.