So we picked up this filter just before the weekend, since our old one was shot (basically had it sealed up with silicon caulking just to hold on.

Got a pretty good price on it, brought it home, then noticed the weird bit. The multiport valve (the entire thing) is held on to the tank by this double plastic ring thing. Basically both pieces are floating, you screw them together, do a final tighten with this cheap piece of plastic Scythe shapped thing, then tighted the ring itself with a bolt/nut.

Does anyone else have one of these? Is it working for you? Twice now, I've tightened it as far as it can go, and it appears to match the vague comment in the instructions of "Tighten until you can no longer see the threads". Twice now, it's worked for about a day or so. Twice now, the O-ring/connection has popped off, resulting in several hundred gallons of water pouring into my garage.

Any tips on how to fix this, or this perhaps a defective unit?