A while back I posted about changing synchros in my 745T w/M46, because second gear was troublesome - well, second gear went away completely, and I was forced into option two, swapping in a 240 M46 of unkown age and origin.

The replacement box, an iron case / J-type OD, worked great in 1-4; but the OD did not work. After verifying the electrical signal and solenoid operation, I tore the OD unit off the back of the tranny and discovered the old-style pistons and bits of what used to be O-rings. As a bonus - the cone clutch was cracked around 60% of the disk. I got the updated pistons and rings, along with a new cone clutch. It all went together easily, and I put it all back up in the car. Still no OD - the solenoid clicks, but I get nothing.

Everything else in the OD was pristine - it was bordering on surgically clean. I'm at a bit of a loss to understand why I get no OD action now. Could the relief valve be toast? What else can I check?