sounds like the Guide ear broke. A glass window replacement shop may
sell you one. They spread apart over the glass then snaps together. The
cars I've owned they were in the upper rear portion of the window. There
is a small hole in the window where part of the guide ear snap fastner
will go through.
It may help to remove the window stop block inside the bottom of the
door so you can lower the window more.
Run the window all the way down, install the guide ear through the hole
in the glass , then slowly raise the window & guide the guide ear into
the weatherstrip run channel.
Re install stop block.
1991 Pontiac Bonneville LE
3800 V6 ( C ), Black/Slate Grey
~~~The Former Fleet ~~~
89 Cavalier Z 24 convertible
78 Holiday 88 coupe
68 LeSabre convertible
73 Impala sedan