Question
when one or two of my zones start up the heads don't pop up all the way just gurgle a lot of water around each head. By manually pushing one of the heads they all start to work properly.

Answer
Hey Richard, has this always been a problem, or did it just start recently? Normally when the heads do not pop- up properly, #1 it could be the valve is not opening all the way, and this is caused by the diaphragm being old, and needs to be replaced. #2 there are too many heads on one valve, and you need to eliminate some of the heads, usually by adding another valve. #3 the water source is not turned on all the way, check your main turn on valve, for the system, and make sure it is turned on all the way. This is a good starting point, good luck and have a great day.