I got a new (rebuilt) 700R4 Transmission with an auxiliary valve body. I put it in the other day and test drove it. Since it was a fresh rebuild, I filled the torque converter with a couple quarts of fluid, filled the pan, and slowly put more into the pan while going through the gears with the engine running. In all, 12 quarts of fluid. Goes into gear great and reverse also works good. Pretty soon, I found out it only has 1st gear, it won't upshift at all. I popped the cover off for the governor gear and did some testing. So first off, it did not spin when I turned the driveshaft. I was able to turn it by hand about a 1/5 turn before it stopped, but that also felt like that was pretty tight. It was also really hard to take out, I could not take it out by hand. I finally was able to take it out and I saw that the gear wasn't stripped to bad and it has some scoring.
Is the solution just getting another gear?
How can I prevent this from happening again?
Thank you!

 

I don't think I'd run that gear.

Before replacing it, find out why the governor doesn't turn, and fix it, so you don't tear up another gear.

 

What did the vendor /rebuilder say?

 

The rebuilder said to just replace the gear. I know it can't be that simple. Maybe it is?

 

Might be. Depends on what you find when you pop the old gear off. If the whole thing no longer binds up, then yeah, you'll be good to go with just the gear. If on the other hand it's still bound up, you'll have to dig deeper.