Those have been unobtainable for a long time. Several years ago I posted a note on how to repair them, but I can't find it. Maybe one of the moderators can point it out.
Basically, you can pull the wires out, pull the blue lens off the respective assembly, replace the bulb with a "grain of wheat" bulb, insulate the leads with silicone gasket maker (black or clear) paint it turquoise (get the paint from a craft store) if you need to or pop the blue lens back on, and reinstall it.
I've repaired mine more than once. It takes a little time but it is no big deal.