My L3400 has three positions for the top link on the rear of the transaxle housing which I am not sure how to use. I noticed in the operator's manual that for certain implements they recommend the top or bottom position, etc. Does the upper position allow you to raise an implement higher and a lower position allow you to lower an implement lower, or how does that work? I mostly use a box blade, scrape blade or rotary cutter for the work which I have to do.