Muah,

Dick is right about the brakeing on the retract servo. Also keep in mind, a normal servo is designed to swing about 120 degrees, and a retract swing is 180. Now a servo used on the throttle will sit where it is, because that is what the radio tells it to do. A normal servo used for retracts is told to go further then it can, in order to hold up or down the wheels. That chatter the servo will be putting out is it trying to keep going; it not only draws more current (eating the juice in your battery) but it also puts wear on the servo and you will have to replace it sooner.

Retract servos are a little more then normal ones but are well worth the money. Once you learn how to set them up you'll see that it isn't really that hard to accomplish.

Hope this helps.