The valve stem packing could be the source of your leak. That hex just below the handle can be tightened a little bit to compress the packing against the stem a little. If that fails to fix the leak, the packing may be completely worn out. You can remove the stem from the valve and replace the packing using teflon packing available at any plumbing shop.
Turn that hex one flat (1/6 turn) and see if the leak stops.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.