This is just my guess
The made the 6-" dogleg and to the best of my knowledge they really never had any problems with it.
They made the 52 : Kodiak Magnum Dogleg and they were cracking up like crazy. That was the Typw I. They put out the type II to correct the problem, but it to still was not right. So they put out the type three, whicj as far as I know did solve the problem
Bear replaced every Type I and Type II that was returned on warranty.
I think the reputation of the K Mag Type I hurt the reputation of the Doglegs so bad, even thought the 60" Doglegs were solid, they came out with the style of the K Mag that started in '64, and is the basic style from then on.
I think the problem with the type I was not enough glass to wood contanct where the limbs join the riser.
They extended that on the Type II, but not enough. On a type III the class goes almost all the way to the shelf. This solved the problem.
As far as why the chenge from the '62 to the '63...NO CLUE. Many feel that the '62 K Mag was the best shooter of all of them. But then that is just a lot of peoples personal opinions.