Neil,

You may want to switch back to a readable font, such as Arial, and make
sure your data shows *12345* after you merge.
Another thing to try is using parentheses instead of asterisks (I'm not
sure if that's what IDAutomation uses, but it's worth a shot). The
reason for not using asterisks is because Word will sometimes turn
anything enclosed in them to BOLD.
IDAutomation is a good company (although I hate to say that, since they
are our competitor ), so I'm sure their Code 39 font will work.

Alek Szymanski
http://www.barcodewiz.com