I didn't know anything about the internal mechanics of my LG dryer so I used the schematic at appliance parts pros to understand the moving parts and likely culprit of the noise. Since the rotating drum appeared to be spinning out of balance, I became 90% sure the roller assembly had failed. I bought 1 roller for 20$ and watched the video for belt replacement so I would know how to dismantle the drum. When the roller arrived 3 days later, it took less than an hour to replace and worked perfectly. Saved a bundle over hiring a repairman.