I doubt you can find the part you need, likely you will have to replace the whole faucet. As a person that did it once before, I warn you ahead of time, likely the sink went in after the faucets did and it can be difficult to get back in there. In my case, there was a really small flange that fit the original faucet, and the new plate that goes underneath was much larger. I had to drill and chip out bits of 3/4 plywood using a mirror to see what I was doing. That was years ago, and I still think my elbow bends backwards.
