Forestar, I'm glad to hear that what I posted helped a bit. As you suspect, that carrier should rotate in the bore it sits in. Are you able to get a set of calipers into the bore and check the diameter in a few spots? If it's egg shaped then it may be possible to gently bump it back into shape. It doesn't need to be a perfect fit because once the lock pin 99-437 is in place it's not going to turn. However, it should turn freely until the pin is inserted.

As for disassembling the carrier, remember that all the threads are all left hand. You should start by holding part 99-436 and unscrew part 99-438 by rotating it clockwise. Once it's off, grip 99-436 again and now turn the end of 99-435, again clockwise. It should unthread from 99-436. Once it's out, the whole assembly should then come apart. I've been meaning to make a video of the disassembly process but I haven't managed to do it. I'll see if I can put something together this week.