Do you have a service manual? They are pretty handy.

My pal had this same issue and I have given this same answer to others and it helped them. He chased it and chased it trying to find the issue with the brakes, shoes, cylinders, springs, etc. It wasn’t the brakes at the drums at all. It was the adjustment on the push rod of the master cylinder. He got it adjusted properly by an old boy shop and the issues disappeared. Check this. It likely is contributing to your issue, or might be the real problem.

Last edited by Fox; 04/18/2021 4:55 AM.

1970 Chevrolet C10
Grandpa's -- My first truck -- In progress to shiny
Follow the build in the Project Journal
1950 Chevrolet 1-Ton Dually
"Ole Red Girl"
In the Stovebolt Gallery
More pictures here
1951 GMC 9430 1 ton dually--Shiny! | 1972 Chevrolet C20- Rusty- the puzzle box lid for the C10 | 1962 AMC Rambler American- my wife's
Parts trucks-
1951 GMC 9300 | 1951-GMC 9430 | 1951- Chevrolet 1300