I have a Waterproof 2075 servo and all the gears are good but the motor it's self slips. I took the servo apart and I can hold the axle coming out of the motor and the motor still goes but no movement. Is this common, because this has never happen to me and I have never seen or heard something like this. I am guesting I will need to buy a new one since you can't really get into those motors. Thanks for any help.