Try cutting out the triangle of your deck, grind back the lower rectangle support to a taper toward the blade and run with the deflector about two inches upward or wide open since nobody lives there and see if that will keep the deck clean. Maybe spray the underside of the deck with teflon and that also may make things better.
Good luck.
Oh, you may want to drill some holes in your belt cover to save your deck belt, pulleys and bearings in the spindles.
First photo is of Tom's belt cover and my personal favorite, however, my covers are working flawlessly and don't look too bad. The deck cut out photos I can't give credit to the owner and I ask forgiveness when he sees this due to my forgetting his name. However, you'll see his modification and it looks great.
Max
I'll show you mine and my covers no longer retain anything where they were packing the grass in each mow.
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