Troubleshooting inground cleaning system

I am having problems with the system cleaning the pool. I don't seem to have any pressure as far as the cleaning heads are concerned. When everything was working fine the pressure gauge read around 20, but now it is only running at around 10. I don't think the heads are rotating like they are suppose to either. I run the system at night and when I check the pool in the morning there is a fan of clean area in front of the heads but there is what looks like sand everywhere else with a heavy amount in the deep end. I have to sweep it every day. I do live in Arizona and we have had a lot of wind off the desert, but I just don't think that is my only problem. The gauge on the filter is just under 30, it usually is around 24- 26 when it's been backwashed. We backwash when the gauge goes above 30.
One other thing, and I don't know if this has anything to do with it or not, but Monday morning came out and pump had blown breaker because motor had stopped working. Took it to shop and they fixed the motor and it is working fine now.
I have the Caretaker in-ground cleaning system with 15 heads, Challenger pump, emerson 1.5hp motor and triton II sand filter cleaning an 18k gallon concrete pool. Like I said it was working fine up until the last 3 weeks or so. I read the book that came with the system and the only thing it says is if pressure isn't at the required level to call a service tech. We inherited the system with the purchase of the house.
Does anyone have any ideas on what my problem might be?