The motor is running but the dish doesn't move or only moves one direction? The acme nut might be partially stripped, or gears inside the "transmission" are not meshing properly.
However if the motor only "runs" one way and not the other try powering it with a 12v battery, switching polarity, and if it works both directions you may have a bad controller. Be careful when hooking up the battery though and make sure you are connecting the "motor" leads and not the sensor! Sounds like you may have made this test already though.
How old is that actuator and how often do you use it? Might be a unit to avoid if it isn't very old. The one I use here is likely 20 years old or more and I use it every day on a solid 10 footer, and still works well but there is a bit of play in the acme nut. A bit of low temp grease once in a while minimizes the play so it's acceptable.
Maybe there is a way to service your new one so it lasts longer. Not familiar with the Sadoun unit but it can't be that different from the others. Check the old one, maybe the acme nut or gears can be replaced so you have a spare?
