Update, with thanks for the earlier posts and recommendations (and yes, the video in Post no. 3 was very helpful!):
While removing the clamshell, confirming that yes, indeed, it has a twist in it, I found this item in the driver's side clamshell mechanism. Part number shown. There wasn't a similar one of these on the passenger's side.
Anyone recognize it and know what it (they?) is supposed to do?
Grateful for any clues!