Phew!
My friend and local amateur frame builder Olivier A. came over last night. After 20 minutes of study under a bright light he slipped a piece of cable into the housing and grasped the bent end -- housing and cable -- and tugging and twisting gently got it to move and slide out.

I think the key was having the cable inside as reinforcement. INdeed as I think about it, if the cable is solid, Visegripping it on either end, there is no way the housing can snap. and if the cable moves, the housing has to go with it.

On examination it looks like the metal spiral of the housing had separated and had expanded in diameter slightly under the plastic coating and had friction jammed in the channel- like a blocked artery.

Lesson I guess. Grease your housings well.