Are these day/night shades? If so, there is a little spool at the bottom on the string on each side. Loosen the screw and tighten the spool a twist or so to set the tension. Sometimes you don't even need to loosen the screw.
Mark Anderson - FMCA 351514 - Louisville, KY
2007 Sportscoach Pathfinder 377DS - Freightliner XC
2006 Jeep Commander
Cricket SW3 Personal Transporter