I've done some playing around, I started off by adjusting the cable to give it some more length and it is now hitting the kill switch and stopping the engine. There is no cable tie on mine so it seems that someone has removed it at some stage so I'll replace it and see if I can get the cable as straight as possible and adjust as required.
I've learnt quite a lot during this process as I've never done anything to a mower before except put fuel in so this has been a good learning experience for me. Thanks everyone for your help and advice
