Fleck missing o-ring in brine valve housing(too much water in tank?)

Hi, First post here. I have a Fleck 5600. I have noticed that my water in the brine tank has been shutting off by the float in the brine tank well. From researching and reading many posts here, I have learned that the float is just a back up.
I took the head apart and checked the brine valve and it looks good and I can press to open. I looked inside the housing to fish out the oring and it wasn't there(and not on the end of the valve either). So, I'm not sure if this valve was replaced before when being serviced and they maybe forgot to put the oring in, but its definitely not there. There is no leaking though, which I find odd,
Anyway, my problem is that the brine tank will continue to fill until it hits the float. I have recently raised the float to about 10" above the check valve.(probably 6" higher than it was) My main question is, would the missing oring cause water to freely pass and continue to fill the brine tank?. When I run a regeneration, it sucks all the brine out fine, then when it gets to brine refill, the water will continue to rise. I manually lift the float valve in the well to stop the water. Even when cycle is complete and "in service" mode, If I push the float valve down in the brine tank, the water will refill. Again, could that missing oring be causing this? If the brine valve is closed at the end of a cycle, no water should be flowing into the tank...correct?
The injectors are fine and no obstructions in the .5GPM nozzle. I also inspected the main piston and seals and spacers..they all looked in very good shape. Any help would be much appreciated. Hopefully, it's just that oring.

 

On the 5600 brine piston the bottom o ring often stays in the hole when the assembly is removed. It might allow water to get by and into the brine tank but the other thing to look at is the brine cam in the power head, make sure that the screw is still holding the white shoe like item at say 6lbs or 8lbs, what ever the setting should have been from the start. If that shoe is lose it will open the brine piston longer.
Take the o ring that is part way of the brine assembly down to the hardware store , some thing like Ace hardware and match it with an o ring . I know that the local one here has o rings and there most likely is one that will match up.

 

yes, the screw is tight with setting at 9 lbs. The o ring is not in the hole, I looked carefully.
Should pushing the float valve down cause water to flow into the brine tank? When in service mode, water will still enter the tank at a rapid rate when I do this. Would the missing o ring cause this?
I have ordered a new o ring along with a new brine valve.

 

If you have on order a new brine piston assembly with both o rings , just wait for it to arrive.
but for now look at the seal on the bottom of the piston shaft and make sure that is is good and that the plastic is good, no cuts or bad spots on plastic or rubber as that to can have water going to brine tank.
Make sure drain line is free.

That bottom o ring did not just get up and go by by.... in 25 + years never seen on just go and not leave some forwarding address or some part behind.

 

thanks for the reply again. I know, the o-ring not being there doesn't seem right. My only guess is that it was serviced at some point and not replaced. All seals and spacers look good.
Any opinion on when I push the float valve down that water rapidly fills into the brine tank? I mean, it isn't a trickle, it's like the brine valve is open. When I turn the knob, I can see the valve being pushed down and released as it should..and the valve opens freely when i depress, no debris and the end looks good as does the attached o-ring. But...would the missing o-ring in the hole not allow the valve to shut when the regeneration cycle is completed?

 

update..looks like problem is solved. O-ring came in the mail today, popped it in the hole along with a new brine valve and the valve shuts the water off from filling the brine tank when I manual turn the knob to brine refill. Before, water would continue to flow in and I had to manual lift the float valve to shut off the water. I will run a full regeneration next to see if the right amount of water is let in and valve shuts off the water well before the float(I raised the float to where it should be)