Something doesn't make sense here. If you have adequate pressure and the head works on another zone then it should work on the zone in question.
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Are you sure the sprinkler doesn't have debris somewhere blocking the flow? Perhaps in the fittings the sprinkler is screwed onto?
Try this, with the zone on, put your finger over the stream of water on one of the other two heads to shut the flow off. Does this increase the pressure enough to turn the head?