My wife just got herself a new car and we're in the process of
transferring state and city licenses before we donate the old car to a
charity.

We've obtained transfer documents for the state plates and they've
been moved to the new car (the charity will pick up the old car so it
won't be driven platelessly in the street).

The problem, however, is the city sticker. The City of Des Plaines, in
its great wisdom, needs to get the remains of the old sticker before
they'll issue a new one for the low re-issue fee.  The problem is
getting the old sticker off the windshield.

The sticker is the self-adhesive type that comes on a paper (or
something) sheet which is peeled off, revealing the adhesive. Usually
the only time one needs to remove the sticker is when it's time to put
on the next year's sticker, so the old one may be scraped off and
destroying the old sticker is no problem.

This time, however, the remains of the old sticker need to be taken to
the license office so they may view it. They particularly want to see
the number of the old sticker.

Now I realize that there's no standard sticker adhesive, but I
wondered if anyone has any ideas how to get the old sticker off in as
close to one piece as possible.  A few years ago I went through the
same thing with my car and managed to get enough pieces off to
identify the old sticker and to see the number, but I don't remember
how I did it.

A neighbor has suggested heating the old sticker with a hair dryer
until it peels off, but I'm a little concerned about the heat damaging
the windshield.

Any suggestions will be gratefully received.

-Len