[C320-list] Excessive Rudder Spacing

[Uckert, Kevin]

Between the top of the rudder and the boat bottom are three clear
plastic discs which wrap around the exterior rudder post. This  provides
the necessary spacing to prevent contact with the rudder top and boat
bottom. 

My boat has additional spacing as these discs move freely between top of
rudder and boat bottom. I suspect this is where a slight leak is coming
from. 

Can anyone suggest a fix to correct this issue short of dropping the
rudder and installing an additional spacer disc? I'm thinking
of a packing gland material, not sure if I'm missing something more
obvious.

I have already tightened up the rudder post collar but has not improved
much.

Thanks in advance for your help.
 
Kevin