One of several reasons: (1) the blades need sharpening; (2) you are trying to mow at a higher speed than is required; (3) one or both blades are installed upside down; (4)one or both blades are bent. My best guess is (1) and/or (2).
A Murray riding lawnmower owners manual can be obtained from most Murray riding lawnmower dealerships. You can find the owners manual at most local libraries.
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The blade on that side may be dull or bent due to hitting something. Could also be that the mower deck is not level, or a tire on the opposite side may be low.
31''
no
in the transmittion
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The spark plug gap for a Murray 12 hp riding lawn mower should be set at .020 inches. This is equal to .5 mm.
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