RainSoft AQ40T o-ring replacement (to start)

Finally I MUST fix water softener. Symptoms lead to advice to replace 5 o-rings. Only have owners manual but no diagrams, etc. Where are the o-rings in such a unit? With a diagram, I know I can fix it.

Photo of the unit in question?

Pictures of AQ40T Rainsoft

Are these pictures OK?

The tanks on the left are the charcoal filter tanks so they are irrelevant except I need to replace the charcoal.

But the valve for your softener is of an older style that I am not sure if there are still parts for it..

While they may not have the o rings they still might be found at a place like True Valve hardware store. I found o rings to repair a bypass valve..

I do have a manual on that ,, but it is hard copy and not a pdf file...

There is one piston with what is listed as 3 O rings, that is under the two white wheels, then there is the two flappers that are just to the right of that piston.

Thanks a lot - this is the 1st parts diagram I've ever seen for this unit. This looks very close to what I have. If this doesn't work, then I'll replace the control unit.

The valve stayed the same while the control changed.

The scann is from a book that I got my hands on some 15 years ago while I was working for a company that is now out of business but had me start my own years ago.