'82 300TD will not shift "manually", stuck in first.

[dewehe]

I have an 82' 300TD with transmission issues. So far, this is what I have done:
1. Checked the vacuum lines. Everything is fine (had to plug the one running to the climate control, to be worked on later).
2. Disconnected the kickdown switch under the accelerator pedal.
3. Adjusted the modulator valve

Everything was running adequately (don't want to say well), shifting properly, though sometimes hard and sometimes with a little flare. However, there was an odd problem: it took almost exactly 1.5 miles before the car would shift into second, then it would shift normally. Oddly enough, this had nothing to do with the amount of time the car was running. If I was stuck in traffic, caught all the lights, fiddled around in the car after starting it, etc., the car would still wait about 1.5 miles before shifting into second. I don't think it has anything to do with warming the car up, since it's 100+ degrees here.

Now it will not shift out of first at all. I tried to shift manually, but that does not work either. In L, S or D, I am in first gear. Yes, reverse works fine, and I can shift through the gears easily.

A friend suggested a stuck valve, but did not elaborate.

Any suggestions? I really need some help here, as my husband is making those "you really should get a reliable car" noises again. Soon he will move on to "I told you so", and I can't have that.


DeLoris