What system do you have? Some of them can be re-calibrated from the control pad without touching the control box.
A couple years, I spent a lot of time crawled into that basement compartment, tweaking screws, shimming the box, and trying to get it to level better. Then I found the manufacturer's service manual, and it showed the simple procedure for pressing a couple buttons and calibrating the level position.
I sure which I had known that before I spent hours trying to tweak the position of the control box.