Water distiller reset button malfunction?

I have a countertop water distiller ( brand: Waterwise, model: 4000 ) with a reset button that has to be pressed for the distiller to start working when it has been refilled with water.

While the distiller is working, the reset button is loose.

Once refilled with water and the power cord plugged back in, the reset button can be pressed ( once only, then it gets loose ), which start the distiller, and so on.

Since a whuke, the reset button stays loose, which gives me the impression that the button itself is broken. I don't understand how a reset switch works, so I cannot determine if I have to replace this button or if it might be keeping its loose position because another part of the distiller is defective.

Thank you for your help, guidance and for your advices.