Take a 1/4 inch dowel and put a dab of grease (I use white lithium or Lanocote) on the tip. Stick it up the through-hull from the under side with the valve closed. Move the dowel around to spread the lube on the lower side of the closed ball.

Now go inside and rotate the valve handle a few times. At this point, you want to end up moving the handle just enough to allow the ball to be open just a bit. This will take practice and feel.

Now go back under the boat with the re-lubed dowel. Put it up and through the opened ball of the valve. Youll know it when you get it right.

The idea is to get the dab of lube on the top side of the ball and then scrape it off by pulling it down and out. Rotate the valve handle again and you are done.

This works well on my H28.5 and hope it works for you, too.