Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
Parts are availble from WM and other places. They are simple to repair, mainly cleaning and "O"ring changeout or replace completely at more expense. You might just take it apart, clean everything then put some petrolieum jelly on the O-rings, reassemble and give it a try. It worked for me a few times on our old boat
As Jerry mentioned, you might be able to take the old one apart, replace an O-ring or two, etc. and get it working again ... that is a much cheaper proposition than replacing it altogether.
My old galley faucet was beyond hope, so I had to replace it ... here's what I used:
Installing it was no problem ... it fit into the hole that the old one came out of. I haven't finished rebuilding my freshwater system, so I can't tell you how it works yet. I CAN say that the Evil Empire has gone up $10 on the price since I bought mine (just over a year ago).
Pierre -- I think the head sink was an option. Some (but not all) who have this option rarely, if ever, use it, and just use the area for storage or convert it to a hanging locker. You could take the working faucet from head and put it in the galley sink (which may be more likely to be used). You could then, at your leisure, repair the bad faucet, take the sink out, etc.
It's also possible that both faucets are good, but the supply line to the galley sink is pinched. Switching the faucets as above would confirm this.
I tackled this same problem myself last year, and before I bought anything I removed the galley faucet and took it home to try to diagnose the problem in a controlled (my kitchen sink) environment. Turns out the faucet worked fine. The problem was the little screw clamp (don't know what they're called) that held the hose to the bottom of the faucet had worked loose over the years and was letting air in, interfering with the suction of the pump. I was very pleased that I didn't have spend any money.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.