Do you have the position control lever "up" (set for "position" rather than forward, which is "draft" mode?
There are 4 bolts that hold the lever assembly in place. With them slightly loosened, the assembly can be tapped back or forth, adjusting the range of the lift lever.
A worn cam follower pin or other internal problems could be causing you grief, as well.
For more help, post over at the "N"-specific Forum. Zane Sherman is the lift GURU over there. He has instructions as well as a jig for setting up the lift mechanism.