I guess I'm only joking up to a point.
Because... I haven't got one of those in decent condition, but if anyone got around to actually having one scanned, and uploaded the .stl file, we could all have them printed cheap.
I mean, well, they do seem to fail a lot, and you can't friqqin' find them...
I'm sure they are available, but like you I haven't been able to find them
I've got a few stashed somewhere, and we have our resident 3D Printerman Scotfrog so I'll make contact and see what can be done.
http://www.aussiefrogs.com/forum/citro%EBn-forum/111105-dee-plastic-bits-9.html
Othello in Switzerland is right into reproducing plastic parts for the D but doesn't appear to have these as yet
FABRICATION DE PETITES PIECES PLASTIQUES EN 3D. | Citrothello
Cheers
Chris