Congrats on your new toy. I was going to suggest making your own knob but now it doesn't seem to be as pressing as it was. I would cut out a round piece of hard wood and bore a hole the same diameter as your existing knob but minus a few thousanths. Use a Forstner bit to bore the hole so it has a flat bottom. Then, mix up some epoxy and place the knob in the hole and tap it down into the recess with a good glob of epoxy in the hole beforehand. Make sure the knob is in straight. Let it set overnight. Once you have it in hand, take a rat tailed file and file some grip areas around the outside. It should be great from then on. You do have to be a bit careful about adding weight to the knob because of vibration so stay away from anything heavy. I made a couple of knobs out of 5/16" plywood for my Dewalt and it worked great. Best of luck.