I had the same thing on a 215 I went around with a culk gun on the windows and any place it could get in I had essex boats down twice they didnt find it ,it would fill the front shelf and when you got onto the boat you could see the water run down into the cabin . I took a large torch into the boat at night and get a mate out side to see if the light came through no luck so I gave it back to essex boats
good luck
mark w