Interesting you mention the spinning noise, as I have noticed the same thing in the clutch area - when I turn it off, I hear something still spinning and then a couple seconds later it stops with a clunk.
I will tear it apart sometime but won't be able to do it right away. I imagine bolts or rivets or bushings loose/worn out, as it almost goes away when the clutch engages, chattering the most when it is disengaged.
If I had to take a wild uneducated guess, I'd say it sounds more like you have damaged/misaligned sprockets or chain guide, or too tight/loose of a chain.
I'll definitely post back once I tear it apart and find what it is. I hope you get yours fixed, I'd be curious to know why your cam chain is breaking too.