The Oring is a standard rubber oring, just tiny. I measured it with dial calipers (machinist by trade, so I know how to read them!), and if I had to make a very educated guess it would be a dash 007 which corresponds to 5/32 ID x 9/32 OD x 1/16CS. I did not disassemble the blfc, I just removed it as an assembly to connect the line. The nut for the line and the 2 piece compression ring, spare clip, and brass reinforcement tube to go inside brine tube were in a bag marked "Brine Kit". I wonder if it was part of that but it does not appear to be leaking. I did disconnect the tube at the brine tank during brine fill and it filled a pint cup in exactly a minute, (corresponding to .125 blfc) so I don't think the restrictor is missing. I also gaged the drain flow with a graduated bucket during rapid rinse and got just under 2.5 gal/minute, so that seems to correspond to the 2.4 DLFC as indicated on the valve. I think I need to come up with a better (heavier) method of restraining the drain hose at the floor drain. It is currently strapped to a piece of 4x4 with an elbow on the end of the tube to direct flow down into the drain
I took a water sample of what I was getting, (initially in a blue bucket so hard to see) into a clear bottle, and nothing settled out, so I am guessing that the resin had some fine sediment in it. No gold glitter, and all remained suspended, nothing settled in the bottle, so I don't think I lost a bunch of resin.
As far as the noise goes, it sounds like water flow with a touch of air, not just like water running. The drain hose jumps at cycle change. It undoubtedly has much more flow than the Sears unit which is 1 CF and claims 40k grains capacity per the manual. The old unit (compact all in one) has an approximately 8-9 x 40 tank and the control valve is about half the size of the new unit.
All is clear this morning and tested at 0 for calcium hardness so all seems to be working well. will try air purging as recommended above to see if I can get anything out of it.
Thanks Bannerman!