The first thing I would check is the condition of the finals. Bring along a 5 gal bucket and some tools to grab some oil samples. You need to remove the finals drain plug by sliding the drawbar out of the way. Look for water and metal, you should see this by dropping less than a cupful. Another method is cutting open the finals oil filter above the axle on the left side. Use a tin snips and cut over your bucket and the mess isn't too bad. You'll need to bring a replacement filter (NAPA or AutoZone has them for not many $). Rotten shift lever boots can cause a lot of grief sometimes.
With a solid final drive package, functional hydraulics, 3 sp pto, and 11-15 front tires plus the FIL this is a fair price IMO. I noticed that it has adjustable wheels which is a benefit also.
I have 2 1850's and they are super haying machines and not too bad on fuel also. The 2 speed gives you a selection of gear ratios that is near perfect. The accumulated hrs don't mean too much if the tractor has been taken care of.