My grandpa(age86) always shuts the gas off on his old tractors, and my dad was taught the same thing. Now me & my dad are wondering do we really need to do that. Where does this idea come from?

I have two tractors that I enjoy very much. One is a 1949 Farmall Cub, the other is a 1952 Farmall Super M.
The Cub has a Woods belly mower on it and I use that tractor to mow my lawn, pull trees and wood around, etc…
The Super M is a restoration project and is [...]

Will not run (we are working on it) the starter seems jammed I pulled my dad around on the four wheeler to try to get it run

the tractor use to run after you cranked it for a while. dad says he can get it running again

My dad called me and wants me to move it. I have no idea how to glow it because its been sitting there all winter. Any help appreciated.