So I am knew at this. My Knot Meter needle seems to get stuck at about 3 1/2 knot mark. It is a sealed unit as in as far there are 4 rivets that hold the unit together to the back plate. If I take it out of the wall of the boat and remove the rivets, what am I looking to do? Does the needle pin need to be oiled? I assume there are some gears to be oiled? Anyone taken one of these apart?