Side glass--driver & passenger doors--downstop?

[Chatt69chgr]

Is there a window downstop that can be loosened to allow the window to travel down just below the window felts?  I found such a stop on the rear quarter windows.  The FSM seems to indicate that there is a stop on the regulator mechanism.  Is this correct.  If there is not then how do you replace the window felts?  The window is in the way.  Surely you don't have to take the whole window assembly (including vent window) out to do this.
I have taken the rest of the car apart except for this and, frankly, these regulators scare the heck out of me.  It looks like once you get them out you would never get them back in and adjusted properly.

Also-----there is a little spring in the bottom of the rear window channel (drivers door) that looks like it might hook to little white plastic pieces.  The spring in mine is rusted and appears to be broken in half.  What is this spring for?

[bill440rt]

The rear regulators are very tricky, the fronts are a cinch. They're only held in with 3 small bolts. Remove the bolts, and the slide it forward or rearward to disengage the roller from the lower track. Regulator is then simply removed thru the big hole in the bottom of the door. Install in reverse. There is really no adjustment to the front door glass with the regulator itself, the adjustment is all in the rear run channel & the vent window.

The felts can be replaced with the window in the door. It helps if you have small hands. Roll the window up. You'll need to find where the clips are that are holding the felt on. From the inside of the door, use a flat blade screwdriver to pry the tab loose on one of the clips. Work down the felt doing this until it is removed. Then do the other side. You may want to put masking tape on the window not to scratch it once you get one side of the felts off, as the window may rub on the door a little.
Then, carefully roll the window down being careful so it doesn't scrape on the door. If you remove the regulator, you'll get it to go down a little farther. Then just clip the new felts in from the top. Bring the window up, reinstall the regulator, done.

Good luck! 

[Chatt69chgr]

Thanks Bill.  I remembered that I had taken a regulator out of a B-body several years ago and had put it under the house in the crawl space.  I put on my old clothes and crawled around down there till I found it.  Now I see that the side window downstop is a cam sticking thru the regulator with a bolt that cinches it down.  The cam has a screwdriver slot in it.  You can access it through a hole in the door.  There is a brass stop on the toothed sector that hits this cam.  You can't actually position the cam to allow the glass to be completely rolled down.  Of course, this thing allows setting of the down position of the window.  But that is all academic relative to my question since your solution is much better.  Just remove the regulator and the window will then move down in the channel like I wanted.  Now I'm thinking of trying to remove the whole vent frame assembly from the door, the regulator (first), and then the rear channel.  Plus the key lock and the main door lock before I have the car media blasted.  I see there is rust on the upper surface of the front and back of the door on the inside and I'd like to get access to that to blast it and then treat it (por15 maybe).  This would give me a chance to spruce up all of these parts.  They are in good shape and no rechroming needed.  I'll keep the vent frame assembly together as an assembly.   

[Chatt69chgr]

An update----I got the entire glass, regulators, channels, and frames out of the drivers and passengers doors as well as the two quarter windows. 
If you just wanted to replace the fuzzys on the doors then the secret, as Bill said, to get the wondow down far enough is to take the regulator loose and slide the wheel on it out of it's channel.  You can lift the window all the way up, remove the regulator through the hole in the door, let the window down and have access to the fuzzys.  More or less the same to take the entire window including quarter frame out---there are several more bolts and nuts to take loose.  I did take the rear channel out first---slips out the bottom.
Removing the quarter window assemblies was a challenge.  Got to take panel off, then upper pad and then the fuzzys.  Next down stop and front and rear upstops.  Next, two bolts and remove window.  Next the fore-aft channel.  Then the rear channel and it's roller (it slips out of the frame).  Next, the front channel at bottom nut and then the metal brace it attaches to.  Then the top nut for the front channel.  Next, remove the 3 screws on the regulator and the front channel will slide up and out.  The remaining guts will now come out with some manipulation from the front top (must remove the rubber cover---three screws).