I have an irrigation system that is MUCH NICER than the one I had at the old house. The one problem I have is with one head. It pops up and waters fine, but will not retract when the system changes to a new zone. So the head stays up. All it takes is a very light tap of the foot and it retracts. Does anyone have any idea of what I can do? I've read some forums (not on this site) that say spray a little WD-40. I'm a little reluctant to follow that route and would be worried about some kind of deterioration of the PVC. Any ideas?