If the governor's weights are sticking, it will not shift either. If you take the tail housing off, the weights should move freely when you rotate the output shaft. If they are stuck, there is no signal to the valve body to shift the transmission. Been there, done that, have the T shirt.
Craig


2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado