Having spent hours trying to re-string the vent I've realised that I need assistance before I end up smashing it into a million pieces . One of the plastic lugs keeping a string in place snapped off which I've repaired but getting the strings sorted out is beyond me. The two straight strings are in place but I've removed the other two and tried various ways of fitting them. Anybody have any experience of this? Attached are images of the frame and two strings. Thanks in advance