9. Now we need to make a water-proof rubber membrane. Grab the balloon and cut a 1.5” diameter circle out of it. Don't make the balloon circle too big or it will get in the way of putting the lid back on the jar. Obviously the shape and cut of the balloon doesn't need to be perfect, just look at the picture.
10. This step must be done quickly so read the entire step before proceeding.
Clean the inside of the metal lid to make sure no petroleum jelly or dirt is stuck to it, this will assure that our hot glue sticks to the lid. Put a circle, about 1” in diameter, of hot glue around the hole of the metal lid. The glue should be on the inside of the lid now, the opposite side of the rubber coil. See image. Once the hot glue circle is in place, quickly attach the 1.5” balloon circle to the glue and press down all around the circle to make sure it sticks to the glue in all places. Once it is dry a little more hot melt glue can be put on the outside to better hold it in place but don’t go crazy with the glue or it could cause clearance issues with the impeller.
11. Make sure all hot glue is dry before attempting this step. Apply some petroleum jelly to the motor shaft and insert it into the rubber coil. You will see it push on the balloon piece on the other side. Take a needle and touch it to the tip of the balloon where it is pushing out with the motor shaft. We are trying to make a hole in the middle of the balloon, but we want to make a very small hole which is why we are doing it this way instead of just poking the balloon. Once the small hole is made push the motor shaft through the balloon. – see image