Main Shutoff Valve Slow Leak
My first post here - hopefully some of you can help.
My shutoff valve to the main water supply has developed a slow leak. My wife said it's been a couple weeks (in laundry room) and she just let me know tonight.
I have not touched it at all except to turn the valve off and on again. I'm tempted to give the nut a turn with a wrench but concerned about making it worse. My assumption is the next level up to shutoff is at the street and that's beyond me.
A) Should I turn it to the right to tighten the connection? Not sure about any reverse threads.
B) Should I leave alone and call a professional plumber?
The pic attached should show the dark, wet part next to the nut.
Thanks in advance for steering me in the right direction.