David:
  I have fooled around with these clocks a little, years ago.  I have
not seen this happen and I don't know how it could happen.  The usual
failure mode is a fault in the seal of the LCD that makes all or part
of the display completely black.
  Are you sure that it has proper power and ground?
If you have access to a Pick-N-Pull type of junkyard, look for a
replacement from a Golf/Rabbit/Jetta of around the same year.  That's
where I got my replacement.  It has the custom green background rather
than the stock light grey.  :-)

Larry A.

On Fri, Jul 6, 2012 at 1:44 PM, Dave Mcneely <mcneely4@cox.net> wrote:
> Can the background for the dashboard digital clock be restored?  The clock in my 1991 Volkswagen Vanagon GL Campmobile works fine, but I can usually not read it because the background (behind the numerals) is worn off.  Sometimes when ambient light strikes it just right, I can read the numerals.  Thanks, David McNeely