I took the head off and had it cleaned and shaved. Could not find a crack in the head or the block and piston. Put it back together and I still have low compression on cly 3. It has to have a crack or a valve issue, but I looked it over pretty good and had 2 others look at the head. Can there be a crack I cant see??? I know about the "issues" with this motor. It is one of the original models. So what else can I do to narrow my compression leak down?