Old house, vintage bathroom - probably 1940s-era sink. It had a drip from faucet that turned into a steady leak. I took apart the handles and stems (which slide horizontally into the sink face), and found that the stems were bent, the washers shot, and the seats hollowed out. I bought new stems, handles, seats, and washers, but I couldn't get the old seats out. (I used a tapper jammed in there pretty good and tried it with a socket wrench, not to mention other tools, but it wouldn't give). So I finally figured out that if I just stuck in a larger washer, the contraption worked. No more drip.
For about two weeks. Then all of a sudden, the water pressure coming out of the sink was nil. Didn't affect the toilet or shower. And weirdly, it started to improve over the next week or two until the water pressure was almost bearable. And then today it was back to a trickle.
I'm OK if the advice is to trash this old thing. I also got some advice to look at the aerator, though I'm not sure where to look on this sink. If there's an easy fix, please let me know.