As a test to make sure it is counting accurately (not missing any counts), you could mark one magnet, move the motor a lot of steps in one direction and then move it back in the opposite direction the exact number of steps it was moved and see if it still lines up to the magnet you marked. If it is missing any counts, then the sensor would have to be adjusted. When installed with the dish, it will move slower, as it will have a load on the motor.
Looks like a good job.
Looks like a good job.