1971 Honda CB750 K1 Clutch Issues

[codypow19]

I've been working on rebuilding my grandpas 1971 CB750 for the last year. I got it running pretty solid and then went to ride it and noticed the clutch wasn't working properly. The problem is when the bike is put into gear and then the clutch is pulled in, it's not actually taking away power to the back wheel. I first just tried adjusting the cable both on the base plate and at both ends of the cable but no luck. After some research I decided to take it apart to inspect and couldn't find any obvious issues. I measured the thickness of all the friction and steel plates, and they all seemed to be within spec. I bought new springs and cleaned all the plates well. Then soaked the plates in fresh oil and put it back together hoping that would solve the issue, but it did not. I've tried doing a base cable adjustment almost a dozen times and even installed a new one. It appears to get the right amount of cable tension and feels like it should work but still doesn't. I am fairly new to working on engines and after more research still can't seem to diagnose the issue. I'm not sure if this is the right place to post but was hoping someone here might have an idea of what's wrong or something I can try.