I recently purchased a 1980 srv240 weekender and I' am having a difficult time understanding how the head works. I have what looks like a glorified portipotty with the holding tank underneath it. If your looking down at the front of the head there is hand pump on the rear of the left side and a manual flush in the right side. Here is where it gets weird, on the right rear corner of the unit there is a 1 1/2" discharge hose and a 1/2" vent. The vent is simple it leads straight out the side of the boat. The waste line runs back around the side into a T fitting, the top of the T exits straight into the underside of my waste fitting on the deck. The other side of the T fitting leads to what looks lke a macerator pump. On the top of that pump there is a 3/4" hose that leads out the side of the hull to a male hose fitting with a removable cap. The pump works when turned on but just makes noise and doesnt move water anywhere. Is anyone familiar with what I'm talking about? And if so, how does this work? Thank you.