Lower unit lube 50tlrd

[highlifr]

Strange problem...... noticed lower unit lube leaking from upper vent screw on lower unit. I replaced the vent screw seal and fill seal changed out the lower unit gear lube. no water in drained lube. good to go. now after about a month later and maybe 10 hours of use noticed lube leaking from upper vent screw again????? what could cause this a bad screw maybe? any input would be appreciated.

[boats.net]

It is normally the gasket(90430-08020-00), it's best to replace them anytime screw is removed. Inspect housing and screw for damage.