Before I bought the Nutribullet, I ready to make sure you NEVER went over the max line as the unit would leak.....and I have not. However, 50% of the time I blend something it leaks and it is very frustrating. I am concerned for the cleanliness of the machine as stuff seeps down through and come out the bottom. Also concerned it may end up shorting due to the liquid? Not to mention, the mess is a pain. Does anyone have any suggestions? Could it be defective?