How Can I Fix Pull Cord Thread Switch Of Bathroom Mounted DownFlow Heater?

Wifey pulled out the Thread for the Pull Up Cord in the bathroom.It has been a very cold and snowy winter in London this year.So we are heavily relying on the Dimplex FX20 MODEL BATHROOM heater. I Unscrewed the heater,but can't seem to find where to reconnect the pull cord thread?The heater is now on since the switch has come off!!!So what l do is i temporarily removed the fuse,and put it back on to run the heater,but want a permanent solution.Do not want to spend 50 quid,when l know l can DIY this,with your help.