Logically the top of the pipe from the steam-driven computer(?) needs a distinquishable horizontal section going into the machine at the back. It has to be able to clear the depth of the cogs and the horizontal pipe coming out of the middle of the cog on the left. At the moment it gives the appearance of just going straight up.
I think you will have to do this by highlighting a section - in the same way as on a cupboard edge, you've only got a vertical line, but you can 'see' the shape as a rectangle because the lower part is darker, and the left upper side catches the light more than the left lower side.
