1973 Pickup Radio Stuck Tuner

[fixmeplease]

Im unsure anyone will know the answer. i have a 1973 Ford pickup AM radio and I cant move the tuning shaft. There are plastic gears so Im not wanting to force anything. Where would this be stuck? The shaft? The gear? And what do I use to loosen it? Ive never worked on an auto radio before so its new to me. See pics for what Im dealing with. Thanks!