[XP] Case LED doesn't light properly

Hello.

When I turn on my PC, my Power LED doesn't light up fully, or even at all because its hard to see since my HardDrive LED works perfectly, and some of the light could be reflected from the working LED.
But after running my PC for a while the Power LED gets more brighter, but not full power as it was before when I first bought the case, it was working fine then.

The LEDs are really bright blue color.
What could be the problem?
Can I fix it somehow?
I have this habit of switching my PSU off for a night after powering down my PC, could this damage my Power LED from doing it repeatedly.

Thanks

Though rare, LEDs do fail. :(

Have you removed and reinserted the Power LED's motherboard connector a few times (in an attempt to try and clean the contacts)?

What is the voltage reading for the Power LED?

It could also be the power limiting resistor on the motherboard. But if the voltage at the header pins is OK, it's not a hard job to replace the LED, you'll just need to work out how to unclip the front of the case usually to get at it. Then just solder a new LED in place of the old one.