Just after I brought mine (EF) I had the same thing happen, the dealer used a silicon based lubricant in the channels and that freed them up. I can't remember what it was but it was available through Ford spares.
The silicon based spray is one of the best options. Over time Armoural will work to dry and hasten rubber perishing.
I had same probs and dealer gave me a can of Fortron Silicon Lube. To stop some of the mess, get a straw to help aim down the channel. Only needs squirt every couple of months and a few runs up/down.
Dealer suggested also to use the silicon around door seals especially across the lower section.
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