See if you're getting power to the small wire at the starter in the start position. If not you have an issue in the safety switch circuit. it comes from the key generally. How are the battery cables?
Battery is 12 volt, U1 group
Most take a 6 volt battery.
If it is a model from the last fifty years it is a 12 volts battery.
Group size 22f
In most cases a battery drains by itself from not running the tractor. I've had it on a 4020 where the tractor set for a few months and the battery goes almost completely dead. If you think it's more than I'm tellin you here bring it into a John Deere shop to have the wiring checked.
in front of tractor underneath exhaust heat shield
It uses a 12 volt lawn mower engine battery.
12 volts / 160 cold cranking amps
Your statement is false, John Deere is the best tractor.
The Waterloo Boy Tractor was the first tractor by John Deere. They were produced by the thousands by Deere & Co. between 1918 and 1924.
4200 compact tractor among others
Ever wonder what the main color of a John Deere tractor is? The main color of a John Deere tractor is green with yellowish wheels but there are many custom painted John Deere tractor's varying in color.