Frigidaire Dishwasher overflow

Thanks to all who responded to my original question about a leak. My son has taken a look at the machine and it turns out to be an overflow problem, not a leak. While the machine is running through the wash and rinse cylces, water surges through the base of the door by the gasket which I assume is Part # 49 or #50 on the left side of the tray that is adjacent part #3, the hinge. It is actually flowing in around the gasket and then overflowing when it fills up the base door tray. The gasket I’m talking about is a thin white strip that runs along the base of the door. If that is part #49 as has been suggested, how do I replace it. It seems impossible to get to.