Yes that will work, that way you can see if the motor is getting DC power, there are two buttons on the bottom of the motor these will move it left or right, be sure to set it back to zero before mounting it back on the mast.
And try the Diseqc 1.2 settings as Ozumo mentioned.
Or even better, if the software allows it, try buttons for manual dish movement and check that the dish actually moves.
You can also try a reset. From the manual: "In the receivers' menu this function could be named as: RE-ALIGN - RESET - GO TO POS 00 - REFERENCE. In some receivers this operation is automatic."
Perhaps the power does not reach the motor (cable problem) or the motor is stuck after a long period of not using it.
"oxidised connectors" is one of the possible causes mentioned in the manual
These motors also have software limits. If you try to move the dish beyond those limits, it may appear to not work, but then
it is just a matter of disabling the limits (and then if needed setting them to more appropriate values)
The motors DO support usals, so use that (much easier than diseqc1.2 and less work)