LX needles have an led strip in them. There are companies that you can send the cluster to that repair them. I dont believe its as simple as swapping out a bulb unless you have some serious micro soldering skills.
Tanin auto is well known on clublexus.com for repairing lexus clusters and needles as its pretty common on the older models SC, GX, LS etc but somewhat rare failure on the LX. If you mention your are a forum member on clublexus you generally get a decent discount also.