Precision M6300: Power button sometimes unresponsive

On my Precision M6300, the power button usually works fine. But when I close the lid and come back to it hours later, often the next morning after it has been hybernating for several hours, it doesn't turn on at first when I press the power button.

To get it to turn on, I press many times, holding it down for a while each time. Often that still doesn't work so I press on it quite hard -- I leave the plastic cover off to allow pressing it that hard -- and finally it turns on.

The problem does NOT happen if I tell Windows to hybernate, then wait a couple minutes and turn it on. When I do that, the power button is very responsive. It's also very responsive if I tell Windows to sleep, and if I power down for just a few minutes.

For a while it worked if I pulled the power cable and battery, then put the battery back and the put the power cable back in. But then that stopped helping.

Any idea what might be wrong? Is the problem likely to be the little power switch soldered to the mb? If so, and I have basic soldering ability, would it make sense to replace the power switch? The switch nearby for the battery indicator looks the same and I never use it; would it make sense to use use that one?

I'm concered that if I do nothing, one of these days it just won't turn on anymore at all.

Thanks,

Greg