[VACList] How to remove old WBCCI numbers?

["P.C. Wever" <p.c.wever@xxxxxxxxxx>]

Hi Airstream owners,
We are in the process of restoring our 1964 Bambi II. I have the 
following question at the moment:
The red WBCCI numbers on the front and the back of the trailer have 
partially been removed by the previous owner. However some sort of 
gummy material still remains. I think it is the old glue. It does not 
get off with the polish I am using for the aluminium. Should I use some 
sort of dissolvent to get rid of it. I do not want to damage the 
aluminium. Any suggestions are welcome.
Peter and Michaja Wever
Amsterdam, Holland
1964 Bambi II