My tensioner did the same thing too. When I did my 351 kit, I pulled the head cover to find my timing was off by one tooth. Nobody had been in the engine at that point. I figured it was a "Friday" bike, from Kawasaki. Once I pulled the tensioner, I found what you found on your bike. I was pretty concerned. Once I pulled the clutch basket, I found teeth in the pre filter screen. After looking around for a bit, I found that I had broke one and a half teeth off of my crankshaft. At that point, my $600 upgrade became a $1400 case splitting, do-it-yourself nightmare. I hope yours isn't like mine was. I run a Krieger manual tensioner now.