I have a 4-year-old mixer tap/faucet in my kitchen, and until recently the water would stop flowing immediately when the tap was switched off.
Now the water continues to flow for a few seconds when the tap is closed.
I wasn't able to buy the exact cartridge (left image) so I tried a generic spare part (right image), but the behaviour is the same with the new cartridge. The gaps aren't identical, which may be the reason the new cartridge hasn't helped?
The metal filter/aerator at the end of the spout is clean. The tap underneath the bench is fully on, and the pressure is good.
What do I need to change in order for the water to stop flowing immediately when the tap is closed?