How can I mend my Dualit electric kettle, model no. JKT33a?

Hi - I have a Dualit electric kettle, model no. JKT33a serial no. 2013.17 that heats intermittently. When I press the plastic switch down sometimes I have to hold it down and turn the kettle on its base to find a position in which to get it to operate. Once I find this sweet spot I can then let it boil ok. I suspect some corrosion somewhere and have cleaned all the metal surfaces under the kettle, but have not observed any change. I don’t think it is a mechanical problem, but you never know. Any ideas? Thanks.