Kinetico Q850 - will not draw brine

[JD-SD]

Hello - I have a Kinetico Q850 that will not draw brine. Unit is 7 years old and has a 4x20 big blue pre-filter which keeps it pretty clean. I've scoured forums seeing the best info on this site which is why I'm posting here, hoping someone else has resolved similar issue.
Here's what I've done so far:
- cleaned the salt tank and confirmed the float/tube/line is not plugged and open with suction from line
- fully disassembled Kinetico head per

and and confirmed venturi and all small orifices were not plugged
- lubed all seals/pistons confirming all o-rings were clean and lubricated

When manually regenerating and disconnecting the tank line, there is constant water coming out of the tank line - never any vacuum no matter what the setting on the manual regeneration.
Only thing I haven't done is what this video suggests with same problem:

which apparently is to replace all Level 4 seals. My unit is only 7 years old and all the seals appear to be in really good shape but ready to try that as I don't know what else could be causing the issue. Any suggestions? Also, where can one get Kinetico Level 4 seals? Not easy to find...
Any help, advice, suggestions are apprecaited.
John

 

[JD-SD]

Unfortunately no replies to this post so I will "close" it with what I've learned and done, which hopefully helps others:

I replaced all the o-rings/seals (not the gaskets). Not sure which ones were bad as none appeared damaged. The new seals, heavily coated in silicone grease, returned my Kinetico Q850 to normal operation. At the same time I switched out my carbon tanks - the Q850 is a quad tank system, with lower tanks holding .4 cu ft catalytic carbon. I was debating replacing the resin but opted not to only because it was only 7 years old and should be ok.
Overall, results are good and system works like new again.