If the shank or mandrel does not fit into the collet, it is possible that the collet is stuck within the collet nut. If this happens, remove the collet nut from the tool by continuing to twist it counterclockwise. If the collet does not separate from the collet nut when removed from the tool, push the shank 6 into the hole in the collet nut. This should cause the collet to pop out of the collet nut. Re-assemble by placing the collet into the output shaft and twisting the collet nut clockwise over the collet to tighten it back onto the output shaft.