I have a 20 yr old model 60 that does not stop discharging water I have taken the head appart and cleaned it, but problem still persists any suggestions
Not knowing a lot of the Kinetico units, I would say that the valve that is to close when in service and not cleaning the other tank is worn and not seating right or that the piston that should be closing is not or it to is worn.
You might be able to find either a used control head that some one is selling or get the part from some Kinetico dealer..
With a phillips screwdiver, push down on the center piece of the clear plastic top and turn clockwise slowly. If the water stops, the valve is not advancing to the off position. If not, a drain seal is at fault.