If you're dealing with , the day/night shades that side on 2 or 4 strings.
Then tightening the strings by rotating the plastic mount at the end of the stings on the wall.
Loosen the screw, and rotate the plastic piece 1/4 turn , then tighten the screw.
Note that over tightening , shortens the string life , and if the shades have loosened with use, the stings could be worn, and the shades may need to be re-strung. Kits are available to do this , and come with instructions.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.