A Retract servo is design to rotate 180 degrees and shut off. That means the rods going to the retracts have to be the right geometry so that in the up position the servo travelled the full 180 deg and shut off. Same thing when the gear is in the down position . If there is anything that is preventing the servo from reaching the full 180 deg travel it will stay on and and kill your battery. You will know that its hang up by hearing a buzzing noise. That noise is the servo trying to reach its end travel. It will only shut off if it reach the full 180 deg.
Now some times you may have to bend the wire going to the gear so as to avoid hitting things in the way. Like wing ribs, the connector on the other side of the servo arm and maybe even the wheel when it come up into the bay.You may have to make 2 or 3 bends and still make sure the rod the right length . So start out with a rod that is a bit long and connect it to the retract one side at a time and work it with you hand until its not hanging up anywhere. And oh by the way watch the flexing . Use 4-40 rods not 2-56 its too flexible. Make sure you put the centre screw of the servo in-line with the linkage on the retracts that goes in and out. One more thing use a retract servo no other. The way you set it up is, With the gear down and lock connect the rods to the servo arm with the servo in the down position. Check the travel of the servo from your radio. Retract switch down gear down. Switch up gear up. After you connect both sides work the gears from the radio and make adjustments until the gears lock in both up and down position AND THERE IS NO BUZZING.