all this oil talk is BS... that failure isn't from lubrication, its obviously from some kinda chunk of something ending up in your engine. maybe the clunky noises were from it banging around in there.
if it were me, i'd at the very least split the cases, put new seals on the crank and replace the clutch side bearing... very least... if you want to invest another whopping $6 you can buy a magneto side bearing too!
much easier to split it now and make sure you got all the junk outta there, never know if more chunks of metal are floating around ready to ruin your day again.