Leaking 727

I know Jack Diddley about transmissions. Well, the inner workings at least. I have a 727 that had sat for 18 years in the truck. When I got it running it performed flawlessly but started leaking everywhere. I replaced the seals and gaskets which sealed it up nice. Just sitting and running, and even running the pump in neutral, no leaks. After test driving it and putting it on my lift I found a leak. It's coming from what I think is the front band adjustment, above the shift shaft, and running down. How do I seal this? Can I just take the locknut off and put some thread sealant on it?