When trying to close the pool this afternoon, I couldn't get any air pressure to build up. In the process of checking everything to see what I was missing, I checked the drain plug to make sure it was tight, and it broke off half still in the threads (it is 6 years old and not pliable). I drilled a hole through the center but it got too dark for me to try anything else tonight. So now I have two problems... It's 2020 I should not have expected it to go well. I would appreciate any advice to get the other half of the drain plug out without damaging the threads. Thanks!