D-type OD engages with throttle off, disengages when even a small amount of power is applied. After 15 minutes of this, it works properly and can be switched in and out at will for the duration of the trip.

Details:
OD ran perfectly in my 1800. Instant engagement and disengagement, no kicking back out ever.

Tranny sat for about six months inside. Then swapped 1800-style cover for 122 cover, installed it in my 122 behind the same motor it used to be behind in the 1800. No appreciable change in power being fed to it or anything like that.

Switch, relay, all wiring is new down to the rubber boot on the solenoid. No possibility of engine movement shorting a wire. Connections are tight. Solenoid clicks fine in the garage, hot or cold. Solenoid is correctly adjusted. Filter is clean, entire tranny is clean, in and out.

As it seems to work once the oil heats up, that could indicate a viscosity-related problem. I have tried 80/90 hypoid gear oil, 30W motor oil, and 20W/50 motor oil. Makes absolutely no difference.

If something hydraulic were failing, it would not start working with hotter oil, right? If something electrical was funky, applying power shouldn't make any difference, right? Thought maybe the solenoid wasn't throwing far enough, but seems like they either complete the throw or burn up trying. It's not burning up and it's not blowing the (new) fuse.

I've already done enough speculation for all of us here, so I'd really appreciate hearing from someone who has actually seen a similar condition and knows what cures it.

Thanks!

--Phil S.