Goose, first of all, welcome to the forum. Hope that you enjoy your time here, and that we can find an answer to your problem.

I'm not an expert by any means, but the thing that popped into my head as I read your post is the two detents of the torque converter to engage it fully - torque converter over the transmission main shaft, turn it as it slides back one "thump", then turn and push lightly for a second "thump" of the notch engaging. I expect that someone else will jump in here later in the day with more & better input.