My GSD900G-01 dishwasher leaks where

My GSD900G-01 dishwasher leaks where the hot water is supposed to go into the tub. There's a plastic fitting that seems to be glued to the side of the tub and the hose from the inlet valve goes to the top of this fitting. There are no visible cracks or other damage but there is some rust inside the tub at the fitting. The fitting has two open gaps on it's side which is where the water is leaking out. It looks like the water is supposed to flow past these gaps (which I'm guessing are there to prevent a backflow from the tub to the supply if the supply fails). As far as I can tell the opening into the tub is not blocked. It's possible that the top of this fitting is partially blocked by rust but I can see no way to remove and/or clean the fitting.