Dont feel bad about selling a non working machine. I also prefer buying them not working and if you really dont like looking at it then its time to go. We had the damn thing working lifted the playfield for the photo put it back down and it stopped so its only something very simple just not easy to pin point.
I agree with Daniel.
EMs are not for everyone and there is a market for Project machines. This does not come down to ethics, Rob - if you want to sell it - move it on as a project. Just state that it is a project machine - or a "non working game".
If you were local, I'd fix it for you, just so you can enjoy the machine. Don't let this deter you from EMs - maybe target a working EM from a member here next time you have an interest.
It may be a 5 minute fix - but it has taken a while to get it working - so I understand your position. JP is an awesome machine !