Brine Tank Overflowing And Not Draining+

We have a "Q2" Rainsoft water conditioner unit that has stopped drawing water from the Brine tank. It flows in just fine, but doesn't drain. Also, the plastic tube that the rubber hose fits into, broke app. ½ down, leaving the hose hanging in the water. Is it necessary for the plastic (PVC?) tube to reach nearly to the bottom? (The only thing I can think of is to protect it from being crushed by the salt.) I read on some other posts about a tri-guard. I just replaced ours, and wonder if I reconnected the hoses correctly. There's a short hose going from the unit which I connected to the bottom of the tri-guard, and the one going to the brine tank comes off of the top connection. Is this correct? (I keep thinking I have it backwards. I realized later I should have made a note as to which one went where.) Also, where are the "O" rings located and where can I purchase some from?
Thanks in advance!