Radiator leak from drain valve

I just did the standard flush and fill on my 2000 Grand Caravan. Flushed several times with distilled water, etc. When I refilled it with fresh coolant, I noticed coolant leaking from the drain valve. The valve is in its "fully in" position but there is still a fairly steady drip. What can I do to remedy this ?

I ended up removing the drain cock and, lo and behold, the o-ring had torn. I replaced the o-ring and, voila, problem solved.....