My bathroom faucet leaks a good amount (2 drops per second) whenever the hot or cold water is turned on. It seems to be coming from the central faucet part, not the hot or cold knobs or the supply lines. It looks like it's coming from the "stem" that opens & closes the drain, as opposed to the connection between the faucet and the sink, but I'm not positive. The area under the sink is very narrow and looks like it will be really difficult to work on it.

I was unable to attach the pics, but hopefully these links should work:

Any suggestions? Thanks!