They are very standard LEDs and Marco has them... or had them. I got a few a couple of years ago.
You do need to know how to solder and maybe more importantly... desolder... to put them in.
You might want to take the mothership apart and look at the legs / solder pads of the LED in question because if its an airball, it likely didn't hurt the LED its self, but more likely broke one of its leads, or its solder joint. So before you go to the trouble of getting a new LED, you might try resoldering what you have.
YMMV but I'd do that first.
All of this assumes you know how to solder because it is easy to damage these old boards with too much heat, or pulled traces.