Leaking faucet in bathroom sink

[Flyover]

Pretty much what I show in the diagram. One of the handles, if it's not turned exactly to 90˚, causes the faucet to leak. And sometimes even when it's at 90˚ I have to fiddle with it a bit to get the leak to stop. (The kids, of course, never bother to fiddle with it, so I often find the sink has been leaking for hours since the last person used it.)

And actually, to really get it to shut off after using the sink, you have to turn it as far as it'll go (about 91 or 92˚) and then bring it back carefully to 90˚; if you try to just turn it straight to 90˚ and stop there it'll still drip.

It seems like it shouldn't be possible to turn it past 90˚, so presumably something is loose. Is there a way to tighten it? Is that not the solution anyway?

 

[Snoonyb]

Shut the hot supply off at the angle stop, disassemble the faucet, check the cartridge for damage and debris, and reassemble.

If the problem persists, replace the cartridge.

 

[Flyover]

Update: I had a plumber over fixing something else and asked him to take a look at it. He recommended replacing the faucet, which I am going to do. The new faucet is in my basement ready to install.