I'm starting to get a little nervous about the cam chain and primary chain guides in my '69 K0 750 diecast. The engine has never been apart and has about 20k miles on it. Part of that was sitting for a long time when I had other interests.
It runs great, normal sounds, and I see nothing in the oil. The last few times I have strained it looking for .....stuff...., but nothing shows up. On the other hand, I think any wear would probably come off as dissolved powder in the oil.
So I guess my question is....what sort of deterioration has anyone seen on these guides after 40 years of relatively low mileage use? I.E....will time alone kill them? I don't really want to pull the engine to replace them for a problem that does not exist.

Jim