I have a 2000 Rainsoft brass valve on a whole house carbon filter which I have kept alive with the TC digital timer upgrade. Now the "Push to bypass" black plastic plunger will no move freely between bypass and normal operation. I see that one of the end buttons spins off and I assume that you then push the plunger out to replace the O rings but it wont go past the half way point. What is the trick to getting the bypass plunger all the way out?
Turns out that the trick is to flex the ends of the plastic plunger in all combinations to distort the line of the plunger in the bore as you rotate it every 90 degress and pull it out. It takes a while to find the combinations of positions to clear all 5 o-rings through each bore but it eventually comes out with finesse in one piece. Takes about 15 minutes in each direction.
Turns out I did get the plunger out and replaced it with new o rings and again with a replacement plunger with new o rings. They kept seizing up after a few cycles so I "finessed" it back into the normal operation mode and created a set of gate valves in some pvc plumbing to do the job outside of the valve. While I as at it I incorporated complete isolation and some union fittings so that it it easy to take the filter out and maintain house water.