I had one, but it got ruined over the summer. I've been getting by for now with what I can get on the internets, mainly the COG tech pages, and my previous knowledge. I'm not much for diagnosing new stuff, but I don't forget what I've learned, and I'm pretty mechanically inclined. All engines work in the same basic manner, you gotta get the details for each new one is all.
As for this particular situation, I did an oil change (needed anyway) and removed/inspected the cam chain tensioner. It seems to be in good working order, no bent springs or misaligned anything. I put it back in, and now the original noise is gone, replaced by what is OBVIOUSLY the cam chain smacking into the adjuster at closed throttle, and that new noise goes away with ANY throttle at all. So now I gotta get THAT to stop.
In this light, it really seems to be the cam chain tensioner. I'm still gonna do the piston height test, but probably not until next week.