I don't think you're going to have much luck finding one. I have yet to see an electrical diagram of a video card.
If you post the exact manufacturer/model number of the card someone might be able to find a picture of one and figure out exactly what got broken off. Or if you have a decent digital camera you could take a closeup pic of the area, use a paint program to circle the damaged section, host the file somewhere and provide us with a link to the pic.
That's about all I can think of to help you. Sorry.