Just took mine out at the weekend because it is knackered. It's fiddly but not difficult. I've emailed a firm today to get a new microswitch but haven't had a response yet.
The switch is held in place by a nut and bolt through the unit housing. It appears to be a screw but in fact a nut is held in place by the housing.
If you've found a supplier of the switches that responds I'd be grateful for their contact details.