Leaks such as these are commonplace on most any mast. If it's windy AND rainy, water finds its way into rigging connectors, halyard exits, wherever there is a hole. You probably find less water on a rainy calm day than a windy one.
The fix is difficult, a floor in the mast above deck height with drains above - it's hard to fabricate, and difficult to seal as well with the usual wires extending to the mast base.
By the way, Spartite is not meant to be a seal, it's meant to replace wedges - still needs a good boot at the deck.