Again, an airleak does not come from a bad bearing, but from tolerance between crankshaft and crankcase. If a bearing would be completly airtight, it would have ALOT of friction. Remeber, 1:8 track engines runs with a steel shiled bearing for less friction.
But afair that vacuum hole starts before crankshaft-case contact area, therefore crank seal has nothing to do with leaks thru vacuum hole. Or i'm missing something?
Anyway, what is a proper way to clean outside of the uncapped front bearng? I know there shouldn't be air compressor, but what about soft brush?