I also have a flaccid key unit where the spring and locking mechanism are not working.

Quote Originally Posted by dhayner View Post
When you pop open the battery compartment, a small Torx screw is exposed. I didn't proceed further, but I'm quite sure that unscrewing this will allow access to the key and probably to the spring. Next step is to find a replacement spring at a hardware store.
I did the above procedure this evening (unscrewed the torx bolt) and the top (key section) of the fob does in fact seperate from the bottom (electronics/battery section).

It appears as though the top (key section) of the fob is a sealed unit. There is a seam where two halves of the top section join but it appears to be fused together. I could not see the spring or locking mechanism. I assume you can get a blank key recut for a lot cheaper than replacing both the key section + electronics of the bottom fob section, but I haven't checked with my dealer.