Power Switch on Olympus E-510 requires too much force

Much like the title — the power Switch on Olympus E-510 requires too much force to turn on.

If I flip the switch normally, the screen doesn’t turn on; when I turn it back off, it does the sensor cleaning sound (3-4 bumps).

If I flip the switch and continue to press on it with a bit of force, the screen turns on and the camera functions normally.

How can I clean or fix the power switch on the Olympus E-510?

Thank you!