A couple zones would not come on and it would get stuck on one zone and would not turn off.
After we figured out how this engineering marvel operated and the replacement seemed a bit out of our price range, we decided to make a replacement.
First we removed the old controller. Turn off the water before you start. Otherwise, your sprinkler system will come on and you'll have water gushing all over the place.
We came up with this little idea. 6 manual John Guest valves with one side connected to the zone tube and the other end connected to the drain line. It is important to insure that all of your valves dump to the drain line, otherwise your wall will look like the one pictured.
Now opening each valve will turn on that sprinkler zone.
Replacing this manifold with an updated sprinkler controller with all the bells and whistles (rain delay, seasonal, odd or even watering, etc.) is easy.
I put our replacement in an Orbit cabinet so that it could be locked.
********************* Reader Contribution **********
Mike From Michigan shared his layout of the valves. He removed the center post and using a mix of pneumatic and john guest fittings, he was able to get 7 valves in his cabinet. I think it's a master peice of field engineering.