Six months later I cleared a spot in the garage and started poking into it a little:
Just as I thought, complete failure of countershaft bearing. Chain wasn’t too tight (I had actually checked it on the side of the road), I’m pretty anal about it being within Kawasaki spec.
Anyway engine has to come out. That LH case may be trash, I’m not sure if the case damage goes beyond the seal mating surface. If it’s just the seal mating surface I may be able to get away with building up epoxy to rebuild the area that a bearing ball exited from.
