Motorcycle Repair: cb900c cam chain noise, slider bar, cb900c

Question
I recently bought a 1982 cb900c with 44k. I drove it for 1000 miles and one day when i arrived at work i herd noise from the cam chain (2000rpm or lower, really bad at idle). I went home and tried adjusting both tensioners but the noise didn't go away. The local dealer said its the tensioner (about a 2 min diagnosis)So i took the topend apart to inspect, only thing abnormal (to me) is the exhaust chain tensioner was fully engaged and theres still slack in the chain. Question is, is it possible that the chain is stretched, like can it happen within a 35mile trip? or did something fail with the tensioner assy? I would like to spend as little as possible to repair, so i would prefer not to take the engine apart. Any advice would be great!!

Answer
I guess something can fail at any time but I think the dealer is probably right.  If the tensioner is applying tension, the cam chain will not have any looseness.  I'd bet if everything looks okay, the tensioner mechanism is just stuck.  The pinch bolt on the front of the cylinder head locks a sliding bar in place when it tight. If you  loosen the pinch bolt it allows the bar to move powered by the spring mechanizm so only the spring is applying the tension on the cam.  

Is the spring look to be in place and undamaged? If everything looks okay, try using a screw driver and push on the upper tensioner slipper assembly once you have loosened the pinch bolt. It may snap or at least free up a little so the spring can apply the right tension to the chain.  I've seen something like this happen on the old CB450s where the sliding bar get rusty and freezes up in the bore preventing the spring from applying tension to the chain.  However, on your engine that's all enclosed and bathed in oil so I can't explain why it's froze up or why it would suddenly loose the tension on the chain.  If nothing is broken or worn out the pinch bolt was unable to prevent the slider bar from moving and it's now jammed in the bore.  That's my best guess.  

Good luck
Rich