Tap will not shut off

[garash]

Our mixer/post tap on the bathroom basin will now not shut off completely. It has always been stiff to operate so I am thinking could it have been Ill fitted? I do not think this is being caused by lime scale build up because it has always been stiff. This
Now brings me to the cartridge, can one of these be fitted incorrectly? As I have said, the tap lever has always been stiff. It is currently running water slowly but more than a drip. How do I deal with this if I dismantle the tap? I don’t really want to buy a cartridge unless or until I have inspected the tap

 

[Newboy]

It has always been stiff to operate so I am thinking could it have been Ill fitted?

Unlikely.

Now brings me to the cartridge, can one of these be fitted incorrectly?

Yes, an incorrect cartridge or not seated correctly but as this would have been installed by the supplier during manufacture this is unlikely.

How do I deal with this if I dismantle the tap?

The most likely cause of the tap dripping and the drip rate increasing is that the ceramic discs in the cartridge have either worn or damaged by limescale - a minute scar on the face of one of the discs will cause the tap to drip. You will not be able to see the face of the discs unless you disassemble the cartridge itself and, even then, it's unlikely you'd be able to see the damage (and even less likely that you'd be able to reassemble the cartridge)

Isolate the tap, remove the cartridge, take the cartridge and the handle to a decent plumber merchant and replace - there are so many variations of cartridge that without the spline count and cartridge profile it's difficult to match a replacement.

If it's a cheap tap then it will cost significantly more to replace a cartridge than to replace with a new tap.