Every Roch B I'VE seen gets wet up there (to some degree). I've rebuilt about 10 of them some of them had different tops. You can try the oil. I wouldn't try the gasket sealer too much fine stuff going on around there. That leather plugger needs to be primed with oil or gas during the rebuild, that may be where your headed again eventuailly. Always keep your eyes open for spare parts. Haveing an extra fresh carb ready to go is always a nice thing. I once got one for four Jimmy Hendrix albums in trade, don't worry I had taped them (twice).
Adios, Kip