Well finally that other shoe I was waiting for dropped on my transmission rebuild. At first I thought something really bad had happened and that it was slipping in third; but I've determined it isn't slipping.

It just really doesn't want to get out of first gear. It will stay in first exclusively until the engine and trans are nice and hot, and then eventually it can be convinced to slowly shift into second, as long as the selector is in 2nd. Sometimes shifting briefly into neutral and then down into 2 will expedite this, sometimes not. But once it finally starts shifting into 2nd, if I try to shift at that point from 2 into drive or OD, it instead downshifts back into first and races; I can only shift back into 2nd by moving the selector there.

This problem doesn't seem to be on that usual "4L60E problems" menu that I often see posted. Do I have a bad solenoid or something?