Not being a Lawyer but rather a wise old owl, this can go down two paths...
One, file a claim in small claims court, have your day with the Judge and see what happens..ask for money but you can request, to the Judge, a swap.
Two, accept what has happened and move on with your life. It ain't fair but $hit happens. Live long enough and it will happen to you too.
The Judge may not award anything based on unknown care by the new owner (who is really at fault that motor broke?)
Doing anything personal will likely put you in hot water. Calling him sounds like a waste of time. If it was fate, he is probably scared and embarrased.
If he doesn't show up in court, its my understanding that the complainant will win by default. SCC cost about $50 to file. Add the fee to your claim for $$
Good luck....perhaps a crew from nc4x4 will show up at your house one Saturday and pull the motor/tear it down/decide what needs to be fixed/take the parts to be fixed/come back and bolt it all together for ya?
Peace and Civility ... read the Bible (Basic Instructions Before Leaving Earth)