Lately my John Deere Z Trak is mowing like crap unless the grass is just really thin. When the grass is just a little thicker (but should be able to easily mow through the grass) is seems like it's trying to mulch the grass. The mower is throwing clumps horrible and it is acting like I'm mowing in the pooring rain. When I'm mowing, grass gets clogged up in the deck as if it's above the blades and I have to go to the edge of the property to get rid of it. When I turn off the blades, a bunch of mulched up wet looking grass drops. In the exact same conditions my scag walk behind with the chute up can easily handle the thicker grass. I have tried re-leveling the deck, which it was a little off and scraping tons of stuck grass out from under the deck. I'm not sure what else to try. Any ideas?