Maintenance on that type control valve depends on your water quality. I would check it after about 6 months. If the screen, hole, or diaphragm have any clogging, then it should be cleaned every six months. If there is no clogging, I would check it again in 12 months. This will give you an indication of how often you should check these things. The principle of operation of these type valves is sound. They were just designed by an engineer who was more concerned with looks and ease of installation rather than function. The Cycle Stop Valve was designed to function trouble free, and it's simple patented design cannot be copied by others for several more years.
You should be able to access all these things by unscrewing the black plastic top of off the valve. On your valve it is underneath and has the adjusting bolt sticking out of it. When the black plastic top has been removed, the spring, bolt retainer, and gut pack should fall out the bottom. The gut pack has the screen and hole that need cleaning. There are several little holes underneath the diaphragm which need to be examined for buildup as well. Then replace the gut pack with the two o-rings, spring, and bolt retainer, before screwing on the black cap and adjusting bolt. If you don't turn the bolt, you should not need to adjust the valve again. Let us know what you find and we can help you with what needs to be done.