It was fairly obvious that a chunk of rubber had come out of the gasket. Ordered a new gasket and in a few hours I was back in business.
My washing machine didn't quite match the one in the video attached to this part, but this one did: http://www.appliancepartspros.com/lg-spider-4434er0002d-ap5592038.html
Nothing was particularly difficult - it was just time consuming. And actually attaching the gasket was especially tedious.