Cam chain roller (idler?) shot

[scum]

I went to start my CB77 the other day and the kick-starter was stuck. I had ridden it around a few times this year mostly around the grounds at swap meets, and once or thrice (unregistered :) ) on the road. Ran fine.
I took off the magneto cover and turned it with a wrench, it turned back ok, but hung up turning forward, so I guess I didn't seize it. I forced it and felt something give and it turned free. I drained the oil to look for metal bits. No metal, but some rubber chunks came out. I removed the oil pump assy and found a lot of good sized rubber chunks in the bottom of the crank case and wrapped up in the cam chain. I figured the cam chain tensioner roller was wasted. I removed the tensioner and the roller was fine. I DID notice that the slider shaft was stuck after I removed the adjuster bolt. Probably was when I installed it- my bad.
I shined a light/mirror down the hole and saw the large rubber cam chain roller was torn up. I probably had the cam chain too tight. So I need a new one.

The question is--can I access the roller by removing the top end? or do I have to split the cases too?

I have a top end gasket set and a new set of standard size piston rings ( both NOS aftermarket) and a spare seized engine. I could try and tear down the spare engine and see if that roller is any good, but I'd rather try to find a new one.
So I guess the other question is can a new one be had?
Thanks.

[LOUD MOUSE]

The CLYMER M331 manual and HONDA parts book will show the location of that part. But I'll tell you the part is mounted to the TOP CASE with 2 bolts so you will need to remove the head and cylinders to replace that part. ..............................lm

I went to start my CB77 the other day and the kick-starter was stuck. I had ridden it around a few times this year mostly around the grounds at swap meets, and once or thrice (unregistered :) ) on the road. Ran fine.
I took off the magneto cover and turned it with a wrench, it turned back ok, but hung up turning forward, so I guess I didn't seize it. I forced it and felt something give and it turned free. I drained the oil to look for metal bits. No metal, but some rubber chunks came out. I removed the oil pump assy and found a lot of good sized rubber chunks in the bottom of the crank case and wrapped up in the cam chain. I figured the cam chain tensioner roller was wasted. I removed the tensioner and the roller was fine. I DID notice that the slider shaft was stuck after I removed the adjuster bolt. Probably was when I installed it- my bad.
I shined a light/mirror down the hole and saw the large rubber cam chain roller was torn up. I probably had the cam chain too tight. So I need a new one.

The question is--can I access the roller by removing the top end? or do I have to split the cases too?

I have a top end gasket set and a new set of standard size piston rings ( both NOS aftermarket) and a spare seized engine. I could try and tear down the spare engine and see if that roller is any good, but I'd rather try to find a new one.
So I guess the other question is can a new one be had?
Thanks.