Here is the complete procedure for adjusting the end stops:

Adjusting the ‘up’ end stop (shutter completely open)
1) Press the ON (I) button on the remote control.  
   1.1) If the shutter stops before reaching the upper position:  Increase the end stop by progressively turning the lower adjustment screw in an anticlockwise direction using the adjustment wrench provided.  
   1.2) If the shutter reaches the up position before stopping: immediately press the ON(I) button to stop it and progressively turn the lower screw clockwise.  Test the up position and restart if necessary.  

Check the ‘lower’ end stop (complete closure)
1) Press the OFF (O) button on the remote control.
   1.1) If the shutter stops before the required lower position, increase the end stop by gradually turning anti-clockwise with the adjustment tool provided.
   1.2) If the shutter reaches the bottom position before stopping: immediately press the OFF (O) button to stop it and progressively turn the upper screw clockwise.  Test the lower position and restart if necessary.