We own a Hayward EC65 DE filter. It has given us twenty years of reliable service and sparkling water. Last year, it began leaking at one or two bolt sites. These are the top bolts that fix the head/cap to the body. When I disassembled the filter for cleaning and winter storage, I also installed a new Hayward gasket. I figured the old one might have become ineffective. This spring, when I started the filter up the leaks were still there. In the past I have tightened the bolts in "opposing bolt sequence". I tighten each bolt and its opposite until all are tight then I retighten them all again. In an effort to stop the leaks I loosened all the bolts and changed my tightening sequence to each bolt then the next. I have managed to significantly stop the leak/drips. I have inspected the filter head and the mating surface on the body. I see no defect or cracks. However, since the leaking is more noticeable when the pressure rises I am wondering if there might be a hairline crack that expands only when the pressure increases and not visible without pressure. Am I on the right track? Thanks