I was looking for a gasket or rubber ring in the tube that the old sensor came out of but could not see one- I felt in the tube with my finger and could feel a rounded ridge that I figured sealed the sensor- didn’t feel much like rubber but maybe it was just old and hard- the new sensor did not come with a gasket so I was unsure if one was reqwuired- perhaps the ridge I felt in the tube is ment to be a permanent, nonreplacable seal? Am I just not appling enough pressure to force the sensor in?