Yes I have replaced a white elf LED that was not working on the 19LED board on my LOTR.

They are just standard LED components that you can buy at an electronics shop. I bought a pack of assorted ones and just soldered in a new white one. You may have trouble matching the exact colour. Check with a meter to see if you have any voltage across the LED on the circuit board when it is supposed to be lit. If you have voltage just replace the LED, if there is no voltage, reseat the board connector first, otherwise you probably have a fault on one of the chips on the board. If one LED is flickering, try reflowing the solder on the LED affected.

I had no problems unsoldering the defective LED. Just push the LED to one side as you melt the solder on the other side and the first wire will pull out through the board. The LED will then pull out completely as you melt the solder on the other pad. Those solder pads are tiny so be careful not to bridge any traces when you do this. Make sure that you fit the LED the correct way round, there normally is a "flat" on one side of the component, or else look inside the LED and align it so that it looks the same. Don't take too long soldering in the new one as these components can be damaged by too much heat.