Cogs and driver cogs in inventory?

[Dave]

I have 3 simple activation and 3 simple driver cogs in my inventory. I have two 'missing simple' cogs on the gate opposite underbrae's guild. I've finished the cog set in the forest and have only just turned in the quest to mother nirn and opened the chest (I'm on a quest now to enter 'sulphur springs')

What are these cogs in my inventory for if not this puzzle?
Why won't they work on this puzzle?
Can anyone assist?

[Chilkoot]

There are a number unused activation and driver cogs in the game that you can find and buy. All the cogs you need for the forest hideout are in that zone littered about, and there is another door in Skara Brae Below that will require 3, which you collect over quite a long period in other zones.

I found this to be a bit buggy, honestly, and I recall having to cheese it to get through the door by the guild. Luckily the reward behind the puzzle door in Skara Brae Below is pretty lame, so don't sweat it too much.