Fixing Venetian Blinds

Daniogroove

hey,
Does anyone have any clue whats wrong with my blind and/or how to fix it?

It's venetian style with the pull string rather than the twisting rod. The strings feel like they have become jammed around the pulley and the blinds will only move about 1/4 inch at most.

I've taken them down, unraveled the string and put it back in but no joy. The pulley looks to move fairly freely when its not hanging up but once its under weight of the blinds if hardly moves. Am I missing something? Or do I need to replace the pulley itself?

Any help greatly appreciated.