Place the tractor on a flat, level surface. Fully depress the clutch pedal, and engage the parking brake. Be sure to leave the key in the off position.
Inflate each tire to 12 pounds per square inch. An under-inflated tire will cause severe deck tilting, and may negate any benefit from deck adjustments made.
Lower the deck and visually inspect the deck wheels. All deck wheels should touch the ground simultaneously as the deck is lowered. If they do not, either the deck is out of adjustment or the deck wheels are excessively worn.
Use the lift engagement lever, and raise the deck to the highest cutting position available. Reach beneath the mower deck and rotate the blades on each side of the mower so that the blades are pointing outwards. Imagine you were sitting on the mower; the left side blade would be pointed at the 9 o'clock position, and the right side blade would be pointed at the 3 o'clock position.
Measure the height of each blade (left and right side of tractor) from the ground surface using a tape measure. The two measurements should be with 1/8 inch of each other. If they are not, the deck is not level.
Locate the adjustable lift link on the left side of the deck. It resides on a bracket near the front left of the mower deck, and has an adjustment nut secured to a bracket. Using a wrench, turn the adjustment nut clockwise. This will raise the left side of the deck. If turned counterclockwise, it will lower the left side of the deck. The idea is to adjust the left side of the deck to the exact same height as the right side of the deck.
Measure both sides of the deck again (height of blade to the ground) and continue to make small adjustments as necessary. When the deck is lowered all deck wheels should contact the ground at approximately the same time. If they still do not, adjust the front/rear deck height settings.
Adjust the front deck height so that it is 1/4 lower than the rear deck height using the front deck adjustment screws (identical to the adjustable lift link located on the left side of the deck--only located at the front of the mower deck). Measurements for this adjustment can be made from the ground to the edge of the deck itself. If adjustment is necessary, use a wrench to turn the adjustment nut clockwise. This will raise the front of the deck. Counterclockwise will lower the front of the deck.
Lower the deck again and carefully watch the four deck wheels. When you are finished making adjustments, all deck wheels should contact the ground at approximately the same time.