Sounds like the idler pulley, although it could be a roller or something stuck between the felt and the lip the drum rides on. The pulley is a common repair. You'll need to pull it all the way apart to change it but that isn't hard. You can see it however just be removing the lower panel and looking in from the right toward the left, the belt goes around it. Behind the motor. If there is a groove in it of lots of black dust that is probably it.

Easy change but use a very fine grit sandpaper ( I use 800-1000 grit) to clean up the shaft it rides on, it'll probably be covered in a sticky black substance. Or replace whole idler assembly.

Whirlpool 279640 Idler Pulley - AppliancePartsPros.com

Pay attention to belt routing before you remove it, you'll be putting belt back on blind and it will be annoyingly stubborn if you haven't noted proper placement. Take pics maybe.