John Deere 400 will not start

I inherited a John Deere 400 from my grandfather and it has been sitting outside for the last few years. I wish I had known about this but anyway here we are. I want to get the tractor rolling again but I can't get it to start.

The tractor has always had various electrical issues and of course after sitting for a few years they're even worse. As I recall from working with the tractor a few years ago the handle on the right side as you are sitting on the tractor has to be pulled just so in order for the tractor to start. I'm not completely sure what that handle is for as the tractor was used exclusively for pulling and never had a deck. I can't find the owners manual or service manual and the tractor does absolutely nothing when you try to start it.

Where can I start to get the tractor going again? I hate to see it go to waste as I did a lot of work with this tractor when I was younger. Thanks in advance!