the on-off switch (button) works twice, and then the razor is dead until it has been recharged, so I don't use it. As a replacement I use an older Norelco razor with a slide switch rather than a button. It works ok but seems to lose sharpness fairly soon. The razor with the on-off button is also Norelco (the newest one I have), and I also have another Norelco (Reflex Plus, which seems to work), and a Braun, which does work.
Both the two newest Norelco units have replaced razor heads, as recommended.