I have had a similar problem with my actuators. Try removing the cover from the actuator itself, exposing the guts, first remove the valve handle. You will see four little wires attached to clips. Jiggle these wires, sometimes they become loose or get a bit of corosion causing them to lose connection. I actually take them off one by one and use a needle nose to close the clip a bit so it is nice and tight when I slide it back on the tab. Be careful though, these parts are fragileand be sure you put the clip back on the same tab you took it from. Otherwise the valve will try to turn in a different direction.