G’day Don, it’s what’s known as a “short shot”. Not enough liquified plastic goes through the mold, leaving gaps. As John says it can be repaired with styrene sheet, Evergreen is a well known brand and is available in hobby shops, bends easy in hot water, ( l made some wheel tubs for another build with it ). If you’re not up for that, put it out on the forum to see if anyone has a spare tub. Good luck with it. 👍🏻