I'll go with the cam tensioner, it looks worn.
Gears, I'm not going there.
My bet is someone has been in here before, cuz #10 nuts were on the inside
Probably didn't need to do this at all except for the leaky gasket. Chain looks pretty good.
Donuts? I don't see no stinking donuts.
Seal is #8....guess that's the crank seal.