Fixing my Creda 37761 dryer?

My dryer sometimes wouldn't turn when switched on. It would very quickly smell of burning. If I pushed the inside of the drum ' to give it a start', it would usually begin turning when switched on. Now it won't turn at all when a few clothes are in it. I've removed the back/side, the black belt around the drum is intact. Help where do I go from here without completely dismantling it?