Using a lube doesn't make up for a properly tapped hole.Yes it may go together better, but the result will be a greater side pressure that will eventually push out to the side and cause damage to the shaft. Anything other than proper tapping of the hole will end with a problem, IMHO. My advice would be to return it to the original maker, or if thats not possible, to someone like KJ, or Rat cues, they will be able to do it right. You will need to send the butt and shaft to them, and they will work it right! If it's tight now, wait until the more humid months. Even with a properly tapped shaft, the humid summer months can make it more tight then when it was built. I can do this work but the above mentioned are closer to you, and have been doing it longer than I, so I recommend them. Good luck,
Dave