Power switch is not working properly

When pressing the power button, the camera turns on, extends the lens, but then immediately turns off. If I hold the power button down, it will stay on, allowing a picture to be taken. However, when I release the power button, the camera shuts off.

Sounds like a problem with the switch itself. I'm very good at repairing things, but would like some suggestions before I open the camera. There is a replacement part on EBay for the top of the camera, but it doesn't appear to include the actual switch (looks like the switch is activated by a pin that moves down when the power button is pushed).

Any ideas on how to fix this?