I just bought a 96 Ranger 4.0 v 6 auto 2WD. The door sticker shows trans code T which I believe is 4R55E. It is not shifting to OD. There are no error lights on the dash. Pressing the OD button on the gear shift lights up on the dash. I feel shifts at around 14, 33, and a very slight change at around 43. I now believe the last is the torque lock up. I tried starting out with OD off, reached highway speed and switched on with no effect. Tried a wild hair and went to Autozone where they connected the code reader. P0761 Shift solenoid, now I an trying to find out exactly what is involved in changing one. Can it be done simply from the pan? I have seen pictures of the valve body and solenoids but nothing that shows it inside the trans. Can this be done with the trans still in the vehicle?

Thanks