I value offerings like this every day on my Case discussion forum and IMO, your asking price is about right for this tractor. It is a bit on the rough side with the chewed up seat and missing headlamp but those are relatively unimportant to anyone looking for a heavy duty grass cutting machine. One thing that hurts it is the "Armstrong Lift" for the deck. This is a hydraulic drive tractor and so people sort of expect the implement lift to be hydraulic as well. The 220 is the entry level model and hydraulic lift was optional at that time. The most important thing is engine condition. If it starts up quickly, does not emit exhaust smoke continuously after reaching operating temperature, then that is a good sign that there are still many hours of use left in this machine. The irony here is that a brand new Ingersoll (new name for this tractor line) today would be about seven grand. Even as a non-running parts tractor, it should be worth at least $250.00 because it will part out for a lot more than that on e-Bay.
But it is getting late in the season in Jersey for most people to think about grass cutting and that may be part of the problem or if you are out in the boondocks, that too can affect interest. Run the ad again at the same price but add "Or best offer" to show you are flexible. I realize that you are just trying to help out the family of your deceased friend and would like to wrap this up sooner than later. Good luck with the sale.
