Because the glides and the felt had failed, the drum was scraping on the glide brackets and wearing a groove in them. They would have worn through completely had I not completed the repair.
I replaced both of the glide brackets, felt pads, and drum glides. The parts arrived quickly and were the correct parts. The videos online showed exactly what I needed to do. I took my time and took pictures of the wiring that I had to unplug and then replug as I reassembled everything.
I'm not 'Mr. Appliance Repair Guy', but it wasn't difficult and I felt like I had enough instruction through the videos to complete the repair and not harm myself or the dryer.