Cam Chain Issue?

[Scrappyike]

I have a CB550 and when I tried to adjust the cam chain, the screw is stuck.  From what I have seen, the screw should not move when turning the nut.  Mine moves with the nut.  I tried holding it with the screwdriver while loosening/tightening the nut but can't keep it stationary.  I am getting a chain rubbing against metal sound from the engine.  Not only that but I cannot get it above 70mph.  At the top of each gear it loses power until I shift up.  Rides fine until it hits the top of the gear and repeats loss of power.

Here is a recording of the sound.

http://s294.photobucket.com/user/pzjgr/media/CB750%20Project/WP_20130730_001.mp4.html

It doesn't seem to capture the sound as accurate as live but hopefully y'all will notice it.

Anything I can do other than take engine out?  Thanks in advance for any help.