When I was a lad of 16, I had a 51 Stude that leaked from the front seal. Twice I pulled it and put a new seal in and it still leaked, although a little less. My Grandpap was a mechanic in the Army after WWI and before WWII. He told me to pull the tranny, remove the seal and polish the shaft with crocus cloth. I did that, replaced the seal and it never leaked again for the 8 more years I drove it. There must have been something on the shaft that, even though it felt smooth, damaged the seal. JS
I for got all about that being over 50 years ago until I kept seeing Doc's troubles.