Mower starts, runs, and mows in posititions 6,5, and 4. However if I drop the deck to 3, 2, or 1 it dies when I let off the clutch. When running in the fourth position if I try to drop to 3,2, or 1 it dies instantly. Have no idea what to adjust? Please help... I like to shave my grass low not on level 4. LOL