Thanks for the info guys. When I bought the car I got 2 keys/remotes. Both had dead batteries but when I put in new ones and re-synchronized them to the car and they worked perfectly. I also polished the lens in the door and trunk with headlight lens polish, came out very nice.
A couple of months later my wife said hers wasn't working very well and at times didn't work at all. I switched keys with her, as mine was working perfectly, and noticed hers looked like the halves didn't fit together as tightly as mine and that the metal key wasn't laying in the recess as tightly as mine. I'm wondering if it got dropped, stepped on or physically damaged in some way. I put in fresh batteries and it seemed OK for a few days but then the infra red stopped working again.
I followed Peter Guenther link,
folding infra red key exchange and got a good idea from pokeyarw's post that something on the circuit board might be disconnected. I found another sale on eBay that sells
OEM cases, so I ordered one with the idea that I'd take mine apart, find and fix anything amiss with the board and then install the current electronics in the new case. For less than $24 it's worth a try.
If it works I'll write up a DIY with photos. Stay tuned, the new case should be here in a few days.