If it was working normally before this happened, and given the fact that it's only moving one click at a time, I'd be suspicious that the magnetic reed switch is bad, or a sensor wire lost connection. I'm not familiar with that particular motor arm, but most have mechanical limits in them. If this one has a metal pin that strikes a micro switch, you may want to check and see if it slipped. Mine is secured with a screw anchored in a nylon nut that runs back and forth on a worm screw that travels from one end of the limits to the other.
You can change the upper limit by sliding the pin in or out. If you need to change the lower limit if it's not letting the dish go down far enough, you'll need to slide the motor arm in the saddle mount to get maximum travel west. (Assuming your arm is on the west side of the polar mount) You can check the reed switch with an analog volt meter to see if it's counting. Most digital volt meters don't respond quick enough to check the pulse. If you determine it's not switching, then you'll need to replace the reed switch.
You'll need to have the two wires unhooked from the reed switch, and the volt meter set to ?, which usually has an audible tone and it will bounce the needle each time the switch opens and closes as you hit the east or west button. If it does, then the switch should be OK. There should also be a pulse voltage on one of the small wires hooking to the switch (+5 Volts). If it's not present, you may have a broken wire, or the actuator control box is not sending the pulse voltage. This is not common, but it does happen. Hopefully, there's something in there that will help you.