I'm saving most of the details for the book, but I can say that this problem is a lot more common than most people think and the book will go into great detail about it. Dave Clements did my first TLA. Alan Harton has corrected several of mine and others, besides. Keith DeHart has corrected a number of TLAs, too. I've been told Jim Stroh and Hamilton Bowen have worked on a couple.
I don't know what clean-up is involved of the mating surfaces after heat treatment if there is no parts deformation. However, I know Alan has had to weld material on to those surfaces with some of mine to correct damage done to the too-soft parts. He had to clean up the weld-ups to get the action right, in those cases.