Orig 1985 250 sx, super low hours, noisy timing chain

[tri again]

I have a funny feeling that the timing chain tensioner is occasionally sticky.
almost positive the oil that was in it was from the factory in 1985 and was never changed
but it was the first thing I did before I even tried to start it.

I'd bet there are less than 10 hrs on this machine from new.
Changed the oil and filter 2x in my personal hour of running but every minute or 2
it sounds like the timing chain gets sloppy for a few seconds.
Normal people can't hear it but I know something's just not right since I have a few other sx and es
models that sound like sleeping babies at idle.

Is the tensioner easy to change?
Will some tiny parts go flying if I take it off from the outside?
Or something to drop down inside and require case splitting?

Manual is not real clear.

Thanks

[atc007]

Yeppers,,2 8mm bolts and out she comes! You will be able to disassemble it on the bench and see if your suspicions are right. The CENTER 8 mm is a " plug",,you will be able to put a small screwdriver in there and back the tension off and see if it is responding correctly.Or,,obviously,just throw one of your others in there also. Very interesting....let us know what you find!!

[250esbigredNY]

sounds like it needs a value adjusted, i guess that will be need.