I plan to abandon the index valve for several reasons.
First it appears that the index valve and controller (KRain 2520) are originals. Zones occasionally are skipped. One of two things is happening. Is the index valve skipping a zone which means the first zone zone ends up getting watered twice? Or is the controller mechanical little trigger finger failing to activate the pump? In that case only three of four zones would get watered (assuming only one skip). How do I know this is happening? The valve should water north, east, south and end with west. After a bit I find it is starting and ending somewhere else.
Second performing maintenance on the system is a hassle because you have to cycle through the zones all the time in order to get back to the one I am testing.
Last occasionally we would like to be able to water only one zone - say for example a zone under repair where lots of water is needed. Can not do with index.
So I am thinking that repairing the existing system is sending good money after bad.