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Rain water coming down the mast needs an exit point, otherwise it will build up to the point of overflowing into the main cabin via the small plastic conduit that is used for wires from the mast that route into the main cabin. This conduit needs to extend up inside the mast by about four inches.
The other route for the rain water to exit is through a weep hole molded into the cast aluminum mast step plate. This weep hole located in the very center of the leading edge of the plate, as seen here in this photo, needs to be cleaned out periodically with a long fine thin brush, a long ear swab or single long plastic broom bristle; something that is stiff and long enough to augur any debris that might clog the hole.