Fuel leaking from aux tank?

[cessnadriver]

Hello ALL. My '65 C337 has been leaking fuel from the aux tank scupper and from a rubber hose under the wing near the inside(small) flap( possibly aux tank vent line). I studied the parts manual. I filled all the fuel tanks the other day and the left aux tank started leaking from the above mentioned locations. I place a bucket under the wing . Today I went back to check on my bird and the leaks had stopped after filling a three gallon bucket. I checked the aux and left fillers, the aux was FULL to the brim, and the left main was down about 5-6 gallons???? I'm pretty sure there is no direct connection between the aux tank and the main tank, except maybe through the sump tank. I'm wondering if it's something to do with the check valves in the scubber line and or the aux tank vent? But how would fuel from the main entering into the Aux tank? Also there is blue fuel stains under the left wing and down the left side of the fuselage? Any advice would be appreciated!
Regards, BILLS