Spray some wd-40 on the neck og the heads then tap them down , then run it and see what happens if some still stay up spray again.
Nestor's Sprinklers
Georgia Contractor
24 years in Business
Vincent Nestor
Nestor's Sprinklers & Lighting
Alpharetta,Ga.30022
vpn1@bellsouth.net
www.NestorsLandScape.com
www.GeorgiaLighting.net