leaking oil from transaxle, where speedo is

[afrodocter]

my speedometer does work so i tested for continuity from sender to dash, and swapped speedometers. i then removed and inspected the sending unit. the gear which resides inside the transaxle did not come out, as it did on a spare transaxle i had lying around. only the unit with the electronics on it and square rotor, which hooks up to the gear in the transaxle came out. i put the unit back in, and now i notice there is oil dripping from the fitting. it is not a fast drip but it is dripping.
why is this? i dont see any o-ring or seal. does anyone suggest against the use of gasket sealer to plug it.?

if this is unclear i can send pics

alex