There are double threads on this-
I don't know about the specifics, but I would be very cautious about anything the seller or the broker say about how it happened or what the lasting impact would be if they get it running again. You (they) need a qualified engine survey and opinion before going any further.
I personally would want to see 100 hours put on that engine before you I would take ownership. Watch out for a quick fix...remember what happened to Barney on the Andy Griffith show when he bought an old car and it had sawdust in the transmission - it thickened the fluid kept it from slipping during the trial, but only for a few days.
remember, there are lots of boats out there.
Twenty years from now you will be more disappointed by the things y%^&*.....oh never mind. 90% of the people on sailing forums already use that as their signature! I'm not a conformist.