[villagetinker]

I see you have not had any replies, this may be due to this being a little more complicated.
I am assuming the valve needs to be replaced this means the water has to be turned off at the meter which typically requires a special wrench. The hot and cold-water valves in say the kitchen need to be opened to bleed off any pressure in the system. The old valve needs to be cut out, and depending on the arrangement of the existing piping several pieces of valves, elbows, couplings, and pipe may be required to install the new valve. IMHO, this may be beyond most of the typical handyman. I would suggest Mike Scott for this work.