Quoted from Glarrownage:
I'll give that a shot. I'm having the same issue with the coffin ramp as well. I added extra washers (as many as I could) but it still didn't push it over enough to keep the flap from rubbing the side.
The coffin ramp you can adjust. Loosen the two screws on the rear bracket holding that ramp closest to the coffin, adjust and re tighten.