Dryer drum won't turn

The dryer drum won’t turn on my old whirlpool. Heats fine. When it’s off I can turn the drum by hand fairly easily. It makes no unusual noise when on. Does that mean it’s the belt?

Sounds like a belt to me. See if there is a video on youtube of dryer belt replacement. Its easy on my Maytag Electric but I’m not sure on a gas model. Good Luck!