Transmission Dilemma - 700r4 no 2nd Gear

[JohnIL]

We have a project crisis on our hands. My teenage son recently bought a '77 C10. One of the reasons he chose this particular truck is that a previous owner had swapped in the drivetrain from a CMT400 (5.7L & 700r4). We were hoping that would keep us from needing to do a drivetrain swap for a while. We're not afraid of the work. We've done it before. But, we were hoping he could drive it, as is, for a few years first. What we didn't realize is the transmission has a serious problem.

Now that we've had a chance to drive the truck a little bit, it's pretty obvious the 700r4 is skipping 2nd gear. All the other gears are strong. It pulls hard through 1st gear, all the way up to 30ish mph. Then, it shifts (slams) directly into 3rd gear. The 3rd-4th shift appears to be normal. Not harsh, not soggy either. Once it's in overdrive, it cruises down the road just like it should.

I'm out of my depth here. Transmissions are full of witchcraft and sorcery. I know engines pretty well, but I've always left transmission guts to the experts.

I stopped by a local transmission shop and described the condition. They theorize that the 2nd gear band is probably toast. The problem is, a full transmission rebuild would cost almost as much as the truck itself. My son can't afford that right now.

So, I hit the interwebz looking for more information. I found references to identical problems on several different forums. I read several posts about possible problems with the 2nd/4th servo. Stuck servo, bad seals, and short pins. None of that is expensive or difficult to work on. I have ordered a new servo, seals, and pin in hopes this will get the transmission back in the game. I'm not terribly confident in our odds.

Here's where I need your help. Does any of this sound plausible? Could the problem be in the servo or am I just wasting time and money? Do any of you have any ideas that might lead us in the right direction? We appreciate any wisdom you can share.

Thanks.
John