I got my '59 Imperial in December, 2001, and it has the exact same problem
you mention, and there was even a note from the previous owners once removed
in the glove box, stating the cars idiosyncrasies, and this was one of them.
Do other '59 owners out there on the list have this same problem? Maybe this
is how they are supposed to work, but I find myself becoming lazy, and not
using my left turn signal, since I have to sit there at stoplights holding
the switch on.
Bill '59 Crown