After a bit more than half a century, the rubber washer in the cold water shutoff valve for the kitchen sink had fossilized:
The hot water washer was in much worse condition:
The shutoff valve for the hose bib in the front of the house, mounted knob-downward, has been dripping quietly for many many years before I replaced it:
I’d turned the valve off to no avail, so this was no surprise:
While it is theoretically possible to replace those washers, even the professionals know better than to disturb a sleeping valve:
The tandem valve was likely installed half a decade ago, along with the dishwasher it services. Perhaps the washer inside remains soft.
The Smell of Molten Projects in the Morning 