Well, try it out! If it has an operating engine, doesn't rap, runs and drives, and digs and plows, thats about all you can ask for!
If it looks nice, seems to have been taken care of, not left to set out in all kinds of weather, has all of its main parts, those things are a plus!
I was given one that had set in an old shed, with a busted connecting rod, a dead battery, two flat tires, and a total lack of care! With a new con rod, and a lot of work making it run, I sold it to a friend,for $250, who is still using it, 7 years later!
Are you sure it is a Troy-bilt? I think MTD is now handling them, for parts.