I am using VX2.4 , update 2.
Somehow my border symbol got corrupted in the central library (the symbol is still there in the library tree but it appears as blank).
Luckily I have a Designer project that implements that border and so I can see the border in Databook - Symbol view (in the borders category).
Within the design I am able to select that border and place it into the various design sheets (selecting it from the Symbol view, not from the central library).
In the Designer's user guide at page 290 there is the export procedure for local symbols (right click and export as a file that is to be imported into the central library).
However the "export symbol" option is greyed out for symbols that are not user-created in the design.