Looks like you have a hydrolic deck adjuster, from what I can tell no adjustment needed.
1. Park tractor on a hard, level surface.
M71478
2. Pull back hydraulic control lever (A) and raise mower as high as it will go.
3. Adjust mower wheels.
M71481
4. Flip open crank handle (B). Crank height control counterclockwise far enough to permit mower to be lowered to surface. Do not turn lever too far, height control may be damaged.
NOTE: NOTE: One full rotation of height control equals approximately 12.5 mm (1/2 in.) of height adjustment.
5. Lower mower to desired cutting height with hydraulic control lever.
IMPORTANT: Avoid damage! Be sure to raise mower before changing height.
6. Crank height control clockwise until it is tight to lock mower in set cutting height. Close crank.
7. To LOCK mower in completely raised position:
· Raise mower as high as it will go using the hydraulic control lever.
· Crank height control clockwise until it is tight. Close crank.