IF IT HAS A WIRE SLIDE SYSTEM, YOU SHOULD BE ABLE TO TIGHTEN IT. THE WIRE SHOULD PASS THROUGH A SMALL METAL BLOCK WITH A SCREW THROUGH IT. UNDO THE SCREW AND LOOK UNDER THE BLOCK, SHOULD BE A SMALL GRUB SCREW (ALAN KEY NEEDED). SLACKEN OFF, PULL THE WIRE THROUGH A BIT MORE THEN RETIGHTEN.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix convector heaters.