Generally, you can't go wrong w/ a 790. I was a Deere dealer for years so know them pretty well. Best tractor they offered. It looks like this one has been used for a 3 pt. mower or cutter. Note the pto (from implement) safety chain hanging
from the left side of the 3pt.. I would say you're pretty safe, what really could be wrong w/ it? Nothing, it obviously hasn't been abused. It still has the pin in the 3rd link. That's unusual. If you find out the SN, you can have a dealer look it up, find out warr. history and even get the name & # of the previous owner. Call him.