You say water is coming out…how much? Perhaps it’s not enough to drive the arms around, as they are driven by water squirting out of the holes. If the water flow from the pump is partially blocked, that could be it. Clean the filters at the bottom of the machine. Also be sure the arms are not blocked by some object hanging down below the racks. This has happened to me a couple of times. Arms turn easily by hand when door is open, but closing the door moves something or other that then impacts the wash arms.