Just picked up a new commercial snapper 21 with 6 hp robin engine, high vac mower. Tried it out at the home this weekend and noticed a problem with the cut. The mower didn't cut portions of the grass that were matted down by the wheels. I have the high lift blade installed. The grass was a little damp, but not wet. Although I was mowing very fast (5th and 6th gear), I thought the mower would have no problems with the high lift blade and hi vac nature of mower. Anyone else have this problem or know how to correct this? I don't have the problem with my JX75 mower, even mowing in 5th gear.