If they're talking about the surface mount, tiny LEDs, those are a PITA to replace. Stern used a light board with those on it in Batman, Dark Knight. Right under the crane area, since there was no room for traditional lamps. Of course, that LED died and trying to solder in a tiny surface mount LED isn't something for the average pin repair guy.

Died... dead, dead, deadski. Meter says power was there, surface mount LED was kaput. Belly up, bereft of life, bought the farm, checked out, done for, expired, offed, perished, pushing up daisies....

"It's dead Jim".

LEDs do die, they don't all last as long as they're supposed to, so some day you will need to replace a dead LED. Take notice of this when you're looking at those surface mount boards.

I think this is the board I was talking about:

http://www.marcospecialties.com/pinball-parts/520-5290-00

There wasn't enough room for the opto board *and* lamp sockets, so they tossed a handful of insert LEDs onto the opto board itself.

$80 if those LEDs die or get the gear and learn how to do surface mount rework.