How do I repair a roll up blind that will not roll up properly in my filing cabinet?

PT, January 2010

at one end of the blind when end cover is removed you will see 2 round slotted plastic discs, insert flat ended screwdriver in slot and half turn, the plastic disc will pop out, turn metal rod that passes through blind that is sprung loaded,until tension is felt hold rod with pliers so not to lose tension then slot plastic disc on the end of rod and relocate in end of blind and turn to lock. P/S roll blind up by hand before starting above instructions

royboy, April 2010

If it a 'spring' only blind, not a pull cord, pull the blind down to its full extend and then let it wind back up as far as it will wind.
In that position, remove the blind from the brackets and roll the remainder up by hand.
Replace the blind in its brackets and pull the blind down to its normal extend.
The blind will now be tensioned correctly which will enable the blind to fully roll up

BlindGuy, February 2010