Hoover TC650 Tumbledryer On button won't stay on?

The ON switch will not permanently stay on, so thinking the switch has broken I have ordered a new switch. The switch that has come (genuine Hoover part) doesn't appear to be an ON/Off switch either, ie doesn't click in to stay ON. So fixing this in will give me the same problem. Can anyone confirm if the button should be a definite on click, click off switch. Because if so then there must be another problem why I'm having to stick the button in with sellotape temporarily.