After our sprinkler system goes thru its cycle of watering the lawn, one hunter leaks, and only one. There is a constant whine in our pipe, the area where I can manually turn off the water with the handle on the pipe. I've replaced the hunter head, replaced the bulb down in the irrigation box. I'm running out of ideas and money try to fix the leak and the whine. Any comments, suggestions will help.

thank you
PeggyG