I have a 15 year old Toro sprinkler system. I order for my zone 2 to work, I first have to turn off the main water supply to the whole system at the gate valve. Next, at the control panel I turn on zone 1 to bleed the water pressure in the system out thru the sprinkler heads. Once that is done, I turn off zone 1 and then turn on zone 2. Of course, nothing happens because the water supply is turned off. I then go back to the main valve and SLOWLY turn on the water supply to the system (if I turn it on FAST it won't work). Zone 2 will begin to work now. I have replaced the solenoid for zone #2 with a new one to no avail. Someone on the "general questions forum" has told me that the diaphragms for #1 and #2 should be replaced. Why the diaphragm for #1? Help!!!