Exmark Quest Belt Squeal

Hi. I have an Exmark Quest with 65 Hours. The last few times I cut grass I could hear a squeal sometimes coming from the pulley on the engine (squeal was coming from behind me so I assume that is where it was) When it made this noise I noticed the section I just cut left some tall grass right down the middle. Does the belt need to be replaced? Is this easy to do myself?

Thank you for any advice.

Mike