We always seem to assume that the outer cover is the culprit but the comet inner primary case can also be taken off and flattened by the same method. You have mentioned Hylomar but have you tried the factory seal - a paper gasket?
There is also the chance of oil entering the screw holes at the joint and leaking out around the heads. Some other makes use O rings under the screw heads although the silicon should work as well.
Cheers
There is also the chance of oil entering the screw holes at the joint and leaking out around the heads. Some other makes use O rings under the screw heads although the silicon should work as well.
Cheers