I recently did some work on my house that required me to shut off the house main water supply. The valve to do that was between the water meter and a Pressure Reducing Valve (I think!) that was made by a company named "Watts." I left the main house water supply valve closed all day while I went to work. When I returned I noticed water had pooled under the PRV (I haven't confirmed that water leaked while the house pressure was off, but now that the house supply valve is open, the leak is very apparent. Upon inspection, it seems water is leaking between the upper and lower brass "hemisperes" of the PRV. My question is this: can I repair the PRV or do I have to have it replaced completely? What other problems could this indicate?

Try shutting off the main and leave close all the faucets etc.

Then slowly open the main valve this may reset the PRV