How to replace a residential valve diaphragm. Do this when the valve is in good shape but is leaking because the internal diaphragm has been damaged.
When sprinklers are still leaking even though the irrigation controller has been turned off, try using the bleed screw to flush the valve first. If that doesn't work then it may be time to replace the diaphragm due to damage. There is a replacement kit that can be purchased at most retailer locations that sell Rain Bird products. This video walks through the short steps to use the kit to fix a valve. This is often a simple project compared to replacing the whole valve.