RussG,
Although I haven't experienced the exact same issue, I do know that Networker won't read barcodes unless you tell it to do so within the jukebox configuration.
The following commands will work in UNIX, if you're using NT type jbconfig from a command prompt on the server to access the same menu. Before you work with the jb_config command, backup your nsrjb.res file found in /nsr/res, this way if anything goes wrong you can restore the current functionality of your jukebox. Quick note: you can open this file with a text editor scroll down to your jukebox info and look for barcode enabled...if it says no read on, otherwise I'm not certain if this info will assist you.
I would shutdown the Networker server by issuing nsr_shutdown, then use the command jb_config to reconfigure the jukebox, you will be asked a series of questions about your exb230d. Somewhere between the 8th and 9th question, jb_config will detect that your jukebox has a barcode reader and ask if you would like reader support enabled. Type yes then, it should ask if you want the volume labels to match barcode labels this is up to you. That should the update your jukebox config, type nsrd to start your NWserver, then nsrexecd to start you NWclients, or if you run some script to start your environment use that.
In Nwadmin, within the volumes view, you should now see the barcodes next to the volume names.
Hope this helps,
Larry J