RE: Servos stop moving intermittantly
It could be a dead spot in the motor. I had some 5625's and some 615's that had similar problems. I talked to the tech at Hitec and was told they had the same motor and it could be the problem. I sent them in and they replaced them.
If a motor has a dead spot in it ( a place where the brushes lose contact) it probably will not fail under the vibration of the engine or under load of operation. It will only be noticeable when you are testing. If it stops , push it with your finger and see if it starts again.