New Mexico......hard water build up in sprayer head.
Remove sprayer head from end of hose......using a rubber band hold the lever open and then drop the whole sprayer head into a jar filled with white vinegar overnight.
The sprayers are installed after the water valve so that full water pressure is on sprayer only when water valve is opened. They do not shut off under full pressure very well....any mineral build up and they can leak.
Also if just problem with sprayer you don't have to replace vacuum breaker also. Sprayer can be replaced using any regular kitchen sink type sprayer from hardware store......hose clamp to vacuum breaker stub out