I have my head off for replacement of the camshaft and some other stuff, and while it's off I figured it would be a good idea to replace the camshaft seal, since it's such a cheap part. So I went around prying at it, thinking it would just pop right out, but it seems to be held in there quite firmly. I kind of tore the rubber up in the process, and a small elastic metal ring fell out the back of it. My shop manual doesn't really cover the subject in-depth, it just tells you to use some kind of special tool to remove it. Does anybody know the trick to replacing this thing?