Here is a picture of an actuator with parts removed.
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The screw on this actuator is rusted, which will cause binding.
A dish mover has to work extra hard to turn something like this.
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Most fta actuators can easily be checked for binding or rough spots in the screw. The easiest way to check is by attaching a volt and amp meter to the dish mover, then move the dish from one end of the arc to the other while watching the volts and amps. The voltage should stay about the same at all times, or at least within a few volts. The amps should steadily increase or decrease as the dish is moved from one end of the arc to the opposite end. Always start this test at one end of the arc, with the dish at the lowest point possible.Binding will show up in the volts or amps as spikes.

The motor itself should be tested in actuators that bind or in actuators that have rough spots. The motor is attached to the transmission and may easily be removed from the actuator. Repeat the volts and amp test on the detached motor. The amps should be steady at start-up and should not changed when the motor is moved from one end f its travel to the opposite end of travel.

If a volts and amp test is not available, then the dish may be observed while moving from the opposite ends of the satellite arc. The dish should not jerk or jump. The amount of force that is needed to move the dish may be found by removing the motor and manually turning the screw by hand. Watch the dish move from the opposite ends of the arc more than once!

A dish that jerks or jumps while moving may have bad polar mount bushings.

A cure for a binding actuator may be simple. Some actuators will have a drip or weep hole close to the motor. This hole should be facing or pointed down, and it allows for moisture removal. Actuators that are binding or ones that have rough spots may be fixed by purchasing a spray can of WD40 and a spray can of white lithium grease. Remove the actuator, turn it upside down and spray WD40 into the actuator tube and directly on the actuator screw. The screw is located in the center of the tube, and the spray can be directed through the weep or moisture hole. If no hole exists, then drill a small hole, being certain that the hole will face down when the actuator is installed.. Follow the WD40 bath with the lithium grease. I prefer to use liberal or large amounts of both WD40 and lithium grease. This is a sealed unit, and attracting dust or dirt to the screw inside the housing should not be an issue. White lithium grease generally will not cause binding issues in cold weather or cold climates. The only alternative to cleaning and greasing is to replace the actuator.

An actuator that does not stop at the same location every time may need the reed switch replaced. It is also possible that the transmission could be damaged (common in binding actuators), or the motor brake system may be faulty.