Re - Tensioning (if required)
Remove the frame from the window
Turn the frame over and release the screw on the barrel clamp.
Pull the loose end of the cord through the barrel clamp to take up the slack and re-tighten the screw to hold the cord in the clamp. Mark the cord to identify how much tension you have added.
If necessary tighten the cord further to hold the blind down in the lower position using the marked cord as a guide.