I take a piece of peg wood and sharpen it to a long taper and insert it into the collet, and select a chuck that will just take the, collet, and put it in the lathe and screw the chuck enough to bring the collet back to shape. You will find it will come back to a perfect shape.
The idea of the peg wood is that it will give enough so it will let the collet back and not break. I have found this method very satisfactory and it saves a lot of work and time. r hope this will help some one as it has me.