Nice to hear you finally got to the bottom of it. Not so nice the $ you had to spend to get there. It's always a major PITA to have to dig into a machine that someone else has "interfered with" previously. Just goes to show that you have to start with basics and don't assume anything. Especially don't assume that because it was "that way" when you pulled it apart that "that way" is correct, as you found with your trans filter bypass spool assembly. Bloody frustrating ........ the error in the manual doesn't help either, because if the manual shows it that way then that's the correct way, right..?
What you refer to as a "sensor" is only an on/off switch BTW.