RIGAS found out that this part is NLA (no longer available). It may take a little doing but I think RIGAS can get more of these. Call us at 877-616-0600 to find out if we we’re successful.
Additional info: this item usually NEVER fails. It’s an infrared (IR) emitting LED (light emitting diode) that is glued in to a holder specifically designed for the NGA-2000 PMD analyzer (paramagnetic oxygen analyzer).