trose348, it is possible to replace all of the important parts inside the valve, if they are still available. I suggest that you obtain an exact replacement valve and use it to replace everything inside the existing valve. While you are there, clean out the valve body. But the problem might be that the solenoid is stuck and needs to be replaced.

I have tried placing my other solenoids in zone 2...but I still have the problem. I installed my irrigation myself, but didn't do the manifold myself. So this is another 'learning' area for me. I will try to get down to the improvement stores to see about what you are saying. thank you for your advice! :)

Ronalawn82 is right - buy the same valve, disassemble it and the existing valve and trade out all the "guts". This is a mechanical problem, not electrical, there's most likely nothing wrong with the solenoid (if it seats properly and is fully closed). The diaphragm in the valve lost its flexibility and wouldn't open - now it's stuck open. Your only other option is to cut the valve out and replace it in its entirety. Depending on how the manifold is piped, this could easily turn into a nightmare. One more thing to think about: 16 year-old system, one valve has gone bad - how long until the other 3 follow?

Well no need for the pic now. I went to H. Depot & 3 dif. ppl. told me my system was way obsolete.I re-did the entire manifold.It took me 8 hrs.to do it. :( Most of the problem was trying to get the plastic box that housed my manifold out. I did not cut the holes at the bottom where the pipes are....I slipped them thru holes I made w/ a key hole punch that you use for doors...can u believe it? I had to get a saw & in the mud, cut it at the bottom. It took 2 hrs. 10 mins. just to get that damn box out. Then after I dug out enough to be able to work I had to get 4 things to complete the transaction. So, full of mud, I went to the home improvement store. Cutting out the old manifold & then exact measuring & cutting the other pvc pipes got me blisters. It took me about 4 hrs. to re-pipe the 4 zones. The other 2 hrs. was for the wiring. I have the Toro jar top valve-slip. The wiring was actually my easiest part.
It's working like a charm & very happy. I knew I put this off for a reason. ARG!!!

I was smart when I did my own system. The manifold is 3' above ground near the pump not in the ground somewhere. I layed out 1" pvc to deliever planty of water and it works great. I now am doing the fine tuning because I've replaced all the heads with the micro irriagtion so I can water 3 times a week and use less water. I added an inline feeding system to feed the garden and need to install a new pressure regulator. It's all set on a timer and takes care of it selt. It's made to be able to remove the valves if needed.