Procedure for Adjustment of Mechanical Motor Limits:

At first determine which one of the below images represents your situation in order to find out, which
adjusting screw is for the top and which one for the bottom limit.

As a general rule for adjusting the shade limit positions, turn either screw counter-clockwise (CCW) to EXTEND the range and turn clock-wise (CW) to SHORTEN the range of the shade, i.e.

Turning CCW - Extends the range (moves the top limit higher, moves the bottom limit lower).
Turning CW - Shorten the range (moves the top limit lower, moves the bottom limit higher.

After turning a screw a few turns, test the result by pressing up / down switch to check the new position
and if not yet correct, repeat this procedure.

Note 1: 

It is important to know that motor limits can only be set if the motor is fully inserted into the shade tube! If the motor has been removed from the shade tube, the tracking ring at the motor head that sets the limits does not turn together with the motor drive and is thus unable to set any limit positions. You MUST install the motor fully into the shade tube and then set the limits.