I found a Scag for sale. 18 HP Kohler, 60 inch cut, 1640 hours on it. Transmission just replaced for $790 by dealer. Seller wants $750. I need a large mower to cut 1.3 acres and I want to cut it quickly. Is 1640 hours something to worry about (used too much)? What specifically should I look for when I check it out? Thank you.