A lesson learned:
I have a B&D grinding tool that had a frozen collet that refused all attempts to remove it.
It had frozen to the shaft.The metal of the shaft was so hard that vise grips could not hold it,even when a gorilla grip,between both knees failed.I finally decided to put a piece of coarse emery cloth around the shaft,rough side on the shaft. Then I applied the vise grips over the emery cloth and the Vise grips were finally able to get a grip,and I finally broke it loose.It was a very stubborn part,locked on by rust.I was afraid I would wring the shaft off before it broke loose.
I had already stripped the internal lock trying to remove it,and did not want to break any cooling fan fins.
I have ordered a new collet and nut,and I will apply Never Seize to the threads so this will not happen again.
The emery cloth trick is a good idea to spread around when working with hardened shafts of any type.