The rails screwed into the freezer cabinet sides for the ice bin were both cracked off at the back end. Possibly a design weakness. The rails are held on by two hex head screws... possibly 10mm?
The rear screws on both sit inside a lipped circle which makes them invisible to see even with shoulders jammed into the freezer. The ice maker housing also interfered slightly....I had swapped out for a manual ice maker unit a while back, so I'm not sure if that's why... I used a Socketflex attachment to get them out. A boxed end wrench might have done the same.
Took less than 10 minutes. The toughest part was knocking the rails off the sides after screw removal: I wasn't sure if it was glue or secured elsewhere; it was just frozen to the cabinet.