Version 2.2 of the hand control uses an index mark on the fork arm to indicate the position where the optical tube is perpendicular to the fork arm. If you purchase or receive a version 2.2 hand control for an older scope without the index mark, or, if your index mark sticker falls off, you will need to make one.
For NexStar GPS scopes, stick tape to both sides of the joint between the fork arm and the rail supports as shown in figure 4-2 in the hand control version 2.2 addendum supplied by Celestron (download the addendum here). Carefully level the tripod and mount the scope. Then perform a GPS alignment and insure the alignment is accurate (good GoTo performance). Then perform the Alt Sensor (the new name for the level switch) calibration. Next, turn tracking off via the menu. Then on the Alt Sensor menu, use the option to move to the alt sensor. This actually moves to the Alt=0 location. Use a ruler and a pen to draw a line across the two pieces of tape to indicate this Alt=0 location.
This tip is also useful if the index mark labels fall off on a NexStar 5i/8i, although you will need to perform an Auto Align (eye-balling the orientation where the optical tube is level) if you don't have the optional GPS module.