I have a sta-rite "system 2" model 150 cartridge filter. The locking ring is a major pain to get off and on - it takes extreme effort to start it unscrewing when taking off, and to tighten it the last quarter turn. Is there a tool for this? I've had no luck finding one on the internet. By the way the ring is about 18.5" diameter. I tried some silicone spray lubricant but it didn't help.