Hi Onetongmc:

The channel that you pulled out the bottom of the door is the (vertical door glass channel guide)and you have (2) per door. Theirs one that is tack welded to the front inner skin of the door jamb and the other is at the rear of the door jam and it's removeable. The rear guide has (3) screws securing it to the door skin. You can see two screws side by side down from the latch when you open the door and their another one hidden almost at the top of the window viewing area on the inside "right under the door glass channel. So to get to the inner screw you'll have to remove the glass and pull what's left of the glass channel out. Those vertical guides keep the glass stable when rolled down and if one is falling apart I can see why the door glass is flopping around. Chevy Duty sells the removable rear channel guide. If it's the front that's falling apart, just have someone weld in a rear guide up front. I did that on my doors.

Joe