If the problem with your Whirlpool 29 inch electric dryer is that is not tumbling properly or is making a lot of squeaking noises. The problem could be a bad idler pulley or idler pulley.
The typical idler pulley was made of a meta bracket and a roller. Since the roller turns with the belt, there is not much friction between the belt & the roller. The only problem with this type of idler assembly is that the plastic roller hole in the center wears out and the roller won't turn properly and makes noises.
They came up with a new design of idler assembly that eliminates the roller and uses a Teflon slide instead. The problem with this type of idler is that there is a lot of friction between the belt and the idler and after a while the dryer starts to make squeaking noises.
When I encounter the idler pulley with the Teflon slide that is making noises, I always replace it with the idler with the roller instead.
Below are the links to the parts needed for this repair.