Morgan 22 centerboard/swing keel mystery fixture

I was helping a friend ready his decrepit Morgan 22 for a sail recently. As I was pumping the bilge, which was full of water from deck leaks, I found a fixture in there whose function was a mystery and I was hoping one the you forum participants could enlighten me. The Morgan 22 has a small centerboard whose case is built into the ballast keel. Forward of that in the bilge as a gland that looks almost as if it could be for a propeller shaft, but it’s definitely not that. Fixed into the gland and projecting forward is a plastic tube. I have no why this through hull fixture is there. Some sort of vent/breather for the board case? The winch for raising and lowering the board (this board has long since been frozen into position) is aft, so I don’t think it’s for that.