DIY Hunter Douglas UltraGlide Repair
If your Hunter Douglas UltraGlide shade suddenly stops working correctly you may be able to fix it yourself!
The Hunter Douglas UltraGlide system is a safe and reliable cord system. It uses an innovative ratcheting mechanism that keeps the cord length consistent. The pull cord passes through an armature as it enters the headrail that controls the locking mechanism. When you pull the cord at around 45 degrees toward the center of the shade, the armature moves a switch, unlocking and lowering the shade. A small tug straight down (or a little to the outside of the shade) moves the armature back over to the locked position. While locked the shade holds it’s position. Pulling the cord in “pumps” and letting the cord retract between pulls raises the shade back to the top.
When the cord gets dislodged from the armature or the channel above it the shade will not operate properly. If your shade is not locking and unlocking or the cord is not retracting this may be the source of the problem.
If your shade looks like the one in the photo below, it may be an easy fix that you can do yourself. Older UltraGlide shades do not have the removable cover, and access to the mechanism requires a more invasive repair. For this reason older units should probably be serviced by a professional.
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Remove the UltraGlide Cover:
Remove the UltraGlide cover by gently unhooking the bottom of the cover as follows:

With the bottom unhooked gently pry the top free with your fingers.

The problem is caused when the cord hops out of the channel between the mechanism housing and the armature. It will most likely look something like this:

Realign Cord in the Channel:
In this case the cord came all the way out of the armature and was off to the side of the guide. Sometimes the cord will still be routed through the armature, but will have hopped out of the guide channel and looped itself around the side. It is hard to see in this photo due to the black parts but should be clear when viewing the shade. To correct the problem start by holding the cord straight out from the headrail and lining it up with the channel as follows:

Route the Cord Through the Armature:
With the cord properly seated in the channel, move the cord back down toward the shade. Look at the armature (the L-shaped black part sticking down from the mechanism). You will see a little flange sticking out to the left (if your cord is on the right side of the shade it will be the mirror-image of this). Move the cord around the flange and pass it through the slot in the back side of the armature.

Replace the Cover:
Snap the cover back onto the headrail. Do a little dance because you just saved yourself a service call by fixing your own UltraGlide shade! Congrats!
How to Avoid the Problem in the Future:
To avoid this problem in the future make sure that you hold onto the cord until it is fully retracted. Letting go of the cord early will cause it to shoot off like a rubber band. When this happens, the cord goes slack and may allow it to hop out of its channel as it recoils.