I've had the same issue as well. I eventually gave up on the tranny and got another. I later had the tranny on the floor upside down. I pulled the filter and valve body off and noticed it looked as if the fork of the band and where the part where thrust pin engages along with another brake ban part was not lined up. I never tried reinstalling the tranny to see if this would solved the problem. You may want to check this on your tranny. Pushing back on the part where the thrust pin engages may have caused these parts to misalign. It seems like these parts take extra special care to reassemble correctly, especially when the tranny is in the car.
I am curious if the same has not happened to you.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012