There should be no rubber .Your cutlass is at the back of the tube where it exits the boat. Pull your Volvo dripless seal off ,maybe someone stuck a cutlass in the front of tube,which should not be there. The purpose of the nipple is to flow water thru the lower cutlass and out . On some beneteaus older ones had a bronze skeg holding the cutlass and do not need the nipple in the tube.You Do have to grease the Volvo every 50 engine hours or once a year and burp it once the boat is launched until your get water ,getting rid of air lock,so water is on the seals .
Check play in your lower cutlass it may be worn if it wasn't getting water supply.
Take a pic after your undo your Volvo drippless ,Volvo says replace it every 5 years ,however you can most likely double that or more ,mine was depends on how much motoring. Use the volvo grease, other types my not be good for the rubber