I have a dripping shower/bath mixer tap (read "running hot water and rapidly getting worse") which I need to fix. I have found the water switch off valves for the apartment, but I cannot close them fully - the apartment is ~45 years old and the whole building is due to have the pipe system changed in the fall so it's probably quite an old valve. There is quite a lot of calcium deposit around the taps so hard water may be a factor.
Here is the valve in the open state:
Here is the valve, as far as I can get it:
How can I get it to close fully? What should (and shouldn't) I do? I'm concerned about applying too much force such that the handle or valve gets damaged and I'd be left stuck without water - is this a risk, and how can I best apply enough force to close the valve while minimising the risk of damage? E.g. is there a way to grip the handle properly? Should I also grip the pipes around to ensure they aren't put under force?
The black tap handle is actually removable, it just pulls of, and reveals that it is just a glorified hex-key. Could I just use a longer hex key to provide better leverage or is there a problem in applying too much force?
I've seen also suggestions of the following too, are they good or bad ideas?
- tap gently with a hammer as I turn the tap
- use spray oil (e.g. WD40) and let that soak in