Question about measuring the cam chain tensioner. Getting the bike ready for summer I wanted to measure the tensioners. I was thinking I would see a rod under the cap when removed but I see what looks like a tube. From what I read on gadgets page Im supposed to measure from the top of the tube (rod) to the top of the threaded body? The best I could measure I came up with is 3/8" of a inch. I have 28000 miles on the bike. Is it time for the extenders? thanks.