I found a set of new old stock rings. The problem is that even though they've never been used, they're so old that the writing on the rings is gone. The "T" or "top" that is usually written on them is no where to be found. I've used a magnifying glass and can't find it! How do I find out which way is right side up? The rings I'm replacing are clearly marked, so I've tried lining them up and looking for a taper, but I can't see anything. The top rings seem to be slightly rounded on top and sharper on the bottom of the ring, so I think I've got that one under control. The oil ring didn't say that it needs to be right side up on the package (top and middle did say that they need to be top side up), so I think that one's fine. It's the middle ring mostly that I can't figure out.