Ok guys..... so I took apart the filter...took it to a pool guy I know.....he looked at it and said it’s nearly impossible to detect where the problem is. Visually looking at it; the 2 plates are fine, o-rings; seal, all looks good. He says it’s the fingers that the DE adheres to.....said just because they look intact, doesn’t mean there arent small holes in the fabric on numerous fingers that you just will never find...... his recommendation ; time to put this 20 year old filter to rest. Thanks for all the input and advice. Greatly appreciated