Ours leaks around the fitting where the vent goes into the tank. The fitting appears to have been installed crooked at the factory. The repair looks to be difficult at best. Our solution is to not over fill the grey tank.
Use of the washer can make for unscheduled over fills. Although the washer drains into the grey tank in our coach just as yours seems to, the owner's manual appears to indicate that it should not do so. The way we read it, the washer should drain into the outlet manifold of the sewer drain. The washer would then not be usable unless the coach is hooked to a sewer. Perhaps that is a better design or, in our case, a good rule.
