terrain data card for GNS won't update

I have 2 TAWS/terrain data cards for my GNS 430W.  Today, I tried to update the obstacle database, and Garmin Database Manager won't recognize the cards-- the yellow light is on the programmer, and the card name flashes briefly on the screen repeatedly for both cards.  iwas able to easily update my navigation data card.  I have seen discussions on other forums of a data card repair utility for terrain cards.  Where can I find this?