I believe someone recently posted that they repaired their leaking low point drain valve(s).
IIRC, they removed the spring on the outside, pulled the plunger up and out of the valve body, replaced the 'o-ring', lubricated with silicone and reassembled.
They took the plunger to ACE or some other well-stocked hardware store and purchased a replacement o-ring.
I hope all that is correct.
Sherm & Terry w/rescue Eydie (min Schnauzer) & Charley (std Poodle)
2015 Jay Flight 27RLS, GY Endurance (E), Days: 102 '15, 90 '16, 80 '17, 161 '18
2006 Ford F350 PSD, 4WD, CC, LB, SRW, Cmpr. pkg, Equal-i-zer 4-p, Continental ContiTrac TR