Did you actually remove the check valve and inspect it? Lots of times it looks good thru the clear plastic but when you remove it, it's not in good shape. 99% of the time it is the check valve.
In order to operate the valves that have the actuators on them, you have to remove the actuator and then use the handle to change the position. If you try to change it with the actuator on it, you can break the gears inside the actuator.
In order to operate the valves that have the actuators on them, you have to remove the actuator and then use the handle to change the position. If you try to change it with the actuator on it, you can break the gears inside the actuator.