Hoover HDV6 start button?

Like several other people on your site I can only get the HDV6 to work when holding in the switch.I got it working by shorting out the old switch while new switch was on order.The new switch is now fitted and I still have the exact same problem. As this switch only makes contact when held in, ( it is not push to on, push to off ) I suspect the fault may be elsewhere on the machine and that overiding it by shorting out the switch could cause problems. Any answers.