12. Now for a real test.  Put the impeller onto the tip of the motor shaft. Just enough so that it stays in place.  Now try to apply power to the motor and see if the impeller spins freely.  A couple things can go wrong here.  The motor shaft may not spin freely due to lack of lubrication on the balloon end or the rubber coil end.  Also, the impeller may be touching the metal lid or balloon and wont spin freely.  Find where your sticking point is and try to remedy it.  I have found that adding extra voltage to my motor will sometimes  “free” it up enough to spin from lubrication problems.  And bending the impeller away from the lid can help also.

13. Once the test above is complete we can try the next test.  Remove the impeller from the motor shaft. Fill the jar ½ way with water and put the cap back on.  The cap should have the rubber coil and balloon installed and also keep the motor in place as well.  Once the cap is on tightly, flip the jar over slowly and look for leaks.  When I attempted this test, mine leaked a little so I had to redo my rubber coil, so hopefully that doesn't happen to you.  My second rubber coil was perfect, not a drop of water escaped during this, or any other, test.  Hold the jar upside down for at least a minute before you progress to the next step, we don't want to get anything wet if we can help it. 
If you like you can try this test again with the impeller on and then add power to the motor to see it working as a “tornado machine” See pictures.   When the tornado starts to spin it pulls air into its vortex, this can create negative pressure inside the jar.  The negative pressure inside the jar makes it unlikely that it will leak during the tornado but after the tornado stops it could leak if a pressure differential was created inside the jar.  Our waterproofing measures hopefully stop this from happening.