Window Winder Worries

Took off the door-skin while cleaning out the cabin to try and shed some light on why the window winder mechanism refuses to catch the cog and move the glass any more. It's a reasonably recent defect to appear [meaning it's likely something my friends and I broke when we were kids] so I feel it my duty to have a look, hoping to find some broken teeth or a loose spindle, but as you can see from the pics there's not a great deal of access to the mechanism. What I could make out though by holding a mirror and torch in the gap, is that the small ratchet that turns the cog is clearly not doing its job, either by being disconnected from the spindle, slipped clear of the cog or even worn away. Unfortunately there's no way of seeing, as the ratchet is totally enclosed within the mechanism and the cog, which looks fine, runs through a channel in it. Getting the mechanism off involves removing the entire glass/bracket/door-lock system, so it's a task best left until we're concentrating on the bodywork.