The Volvo board members seem to be sure that the problem is with either the shift linkage or the kickdown cable. I did have to unhook the shift linkage in order to pull the housing off, so that is a possibility, but I made sure to make note of exactly how the linkage was placed when I unhooked it, and hooked it back up exactly the way it was (I am pretty sure)...
I have no idea where the kickdown cable is. I didn't unhook a cable during this procedure, but I suppose it might have come loose, I dunno.