I just received my new Riva 901 from Liberty Flights a couple days ago and all my carts that came with my kit are pretty loose. They slide out if the pv gets turned cart side down. I store my Riva on its side as to not flood the atty, but the juice starts to seep out between the atty and the cart since the cart slides right out with no resistance. I'm just wondering if there is anyway to make this better or do I just need to order different 901 carts? These carts are the round black, not the whistle tips. I don't particularly like the whistle tips, but wonder if the round just don't fit well in the 901.