When you begin noticing your mower cutting the grass at an angle, the mower deck is out of adjustment. When you accidentally run over small stumps or uneven portions of the yard with the mower deck, it causes the deck to become unlevel. To level a Craftsman mower requires making adjustments to the lift linkages on the front and side of the mower. Ideally the front of the mower deck is lower than the rear with the sides even across the ground.
Park the Craftsman mower on a level surface. Raise the mower deck to its highest position with the deck lever. Take the ignition key out of the ignition.
Go to the right side of the mower and measure from the bottom edge of the deck to the ground at the front corner with a tape measure. Measure the bottom edge of the deck to the ground at the rear corner. The front of the deck ideally should be 1/8 inch to 1/2 inch lower than the rear of the deck.
Locate the two front mower deck links on each side of the mower. The links attach near the inside of the front wheels. The end of the link has two nuts separated by a bracket. To raise the mower deck, turn the nut pointing to the rear of the mower counterclockwise one full turn with a wrench. One full turn equals 1/8 inch of movement in the front of the deck.
Tighten the nut facing the front of the mower with the wrench until it is snug against the bracket. Repeat for the other side of the mower. Each adjustment you make on one side must be made on the other side. To lower the front of the deck, loosen the front nut and tighten the rear nut. Recheck the deck measurement front to back and continue adjusting as necessary.
Measure from the bottom edge of the deck to the ground on each side at the center of the deck. The distance should be the same or within 1/4 inch on both sides. Locate the lift link adjustment nut on one side of the mower. The lift link is directly under the suspension arm of the mower deck.
Tighten the lift link adjustment nut one full turn with a wrench to raise the side of the mower deck. Loosen the nut one full turn to lower the side of the deck. Check the measurement again and adjust as necessary. Only adjust one side of the deck.