Re-tensioning pleated blind on a Fleurette caravan

singinggranny

We have an ageing Fleurette pop-top van that we tow with a classic car. It is in very good condition apart from the push-pull pleated blinds; the side window ones gave up and we couldn't fix them so we replaced them with roller blinds. Now the front window one is loose, I suspect it was got at by the grandchildren during a game of hide and seek! We cannot figure out the tensioning system. The cord winds around small plastic buttons that have come out of the sockets and refuse to go back in. Is it possible to fix them or easier just to buy a roller blind? I've searched online but can't find anything relating to this.