I have tried clicking on both hatches numerous times with no success. Holmes has put the cog he found under the sacks on the left hand side of the mill. Watson has the large cog he found by the room divider. I have tried clicking the hatch when Watson is holding this cog, Watson says 'wonder what Sherlock is doing?' Sherlock just says that he can call Watson. I do not have a action hand when I click on these hatches.
I have gone back to a save point and got Watson to place the cog he found on the mechanism downstairs first then clicked on the hatches with the same results. I am still missing one cog and have gone over this whole episode a couple of times with the same result.
I am loving this game and this is the first time I have got stuck!
Edit: solved it!! simple matter of remembering to
join the chain and the rope!!
Elementary, my dear Watson