I have a Sta-rite plm 100 that is 5 years old. The old filter was extremely dirty so I ordered a replacement. The new filter doesn't seem to sit quite right and I get absolutely no pressure or suction. My system runs great without the filter in, but as soon as I put the filter in I lose suction. I was told it might be dirty, but the old extremely dirty filter worked just fine. Any ideas would be appreciated. I can't find any information or diagrams on line that have been helpful. Local pool techs are stumped and I even called Pentair, the manufacturer and they have no clue. Thank you.