i just bought new batteries 2 day i think i might of got a rock stuck in the servo area cuz the servo was lockd up i changed batteries and no luck i took the servo apart to find the gears lockd tight even with power on. All it would do was hummmmmmmmmmmmm. I also wrapped the batteries with a rubber band when i first put them in. My father in law had the same thing happen to him after i had to call him to tell him what happend