Turned out to be a shredded coupler. $12 part saved me from expensive washer replacement. Fairly easy replacement once I figured out how to get the case open. Video was helpful but not exactly like my washer. Would have helped to be able to get behind the machine which, unfortunately, is difficult in my installation space. Replaced a few other inexpensive items while I was in there. Washer back to perfectly quiet operation.
Big thanks to AppliancePartsPros for making stuff like this available and for providing video guides to help!