The original owner before me kept it inside and I've always kept it inside too.
My wife says it is from the oil in skin that stained them.
I even keep the dash pad and seats covered when it's inside.
I got some courage up today and tried Purple Power on the drivers side armrest.Helped some so,I went to full strength and soaked it.Then, used a very soft brass wire brush on it.
Now,it's looking a lot better,but you can still see the stains,and it looks much better than the passenger side now.
Now,the wife suggests to use ammonia on it.
I'm hoping someone comes up with more ideas before I ruin one of them!
Mike.