Take a can of WD 40 and spray the shaft that the gear spins on. ( make sure to disconnect battery first) after spraying spin the gear up and down the shaft a few times then hook up battery and give it a try. Check the spring to make sure it's not broke. Not sure on your's but some have a nylon insert inside the gear that the shaft goes through. Have seen them wear to the Point they will wobble enough to bind up.