That would be weird if the capacitor wore out. Y'know the maddening thing about many shake lights? They're actually run on button batteries! It makes the LED look bright when you're in the store and when you first use it. I don't remember the particular lights, but I remember reading about this somewhere. Oh, I think it was on the Nightstar website. It's possible that your light was primarily run on batteries, and had a really cheap, essentially useless "shake light" mechanism for show. So, shaking it really didn't do much, although it might have generated a tiny amount of power, so technically it was a shake light. But once the batteries run down, you're out of luck