I feel for you guys but if it was me this is what I would do: In my other life I'm a model railroader and have ample supplies of "stuff" needed to build things. Small strips of plastic styrene, anywhere from a thickness of .005" and up and at widths from that dimension to 8". I just measured the little nub on my old D60 and its just about .080" at the wide end.I would cut a small piece of the strip ( .005x.080)at the same size as the end of the nub and glue it on the nub end with a tiny (real tiny) drop of super glue. This is after trying the scotch tape trick to see if that fixed it. Since very few (if any) of you have this stuff sitting around I would go to a good hobby shop (not a chain store, those guys are retail sellers, not knowledgeable hobbyist) , explain to the owner what you want to do, with camera in hand, and let them show you what to do for a couple of bucks. The worse that could happen is you need to let the plastic fall out of the battery compartment if the plastic falls off the nub. Sorry I don't have a 40D or I'd try it just to see.
