Me too!! I missed my baby!
1...very glad to see you back in the saddle, Chief!
2...very glad to see that if it had to happen at all...it was a failed part, and NOT any custom reassembly back at the Yamaha Plant, by a rebuild tech. That means...that there should be no other problem(s), if your engine was one of the first 500 serial numbers, that was hand-rebuilt.
3...as I was riding yesterday, Chief...(my serial is 042), I got to thinking that I am now quite glad that my bike is of the first 500 that had come off the production line, and were held back due to a misaligned crankcase seal gasket, and then were hand rebuilt to ASSURE that there would be no crank case engine half's, oil gasket leakage! I didn't say it in prior posts, but I really wasn't leaning to the theory that a tech that was assigned to hand-building your engine screwed up with setting the zero clearance valve lash. Of course I didn't know until now, what it was...but that just didn't 'whisper' to me.
So, considering that we all of the '500 Serial' club, have sort of 'blueprinted' engines....before they recommitted the motorcycle builds to the assembly line, and any robotic placements of gaskets or parts.... I very much feel good about that.