I had an irrigation system installed last fall by a contractor. One of my Hunter PGP rotors stopped rotating yesterday. My contractor has not been responsive to my calls and I need to get it fixed asap since I just had my entire lawn reinstalled and I need to keep the yard watered twice a day. I had to shut this particular zone down while I get this issue resolved. Is there anything I can do to troubleshoot the problem on my own or is the head shot? Thanks.