This is AWESOME! My only query is the bottom corners?
It was intentional... I dunno, I just kind of liked the way the chain seems to use more force to move it alone. I know it isn't logical.
I like the upper part very much 
... but it seems like the upper part is slower than the grey toothed part 
(maybe are just my tired eyes 
... but you should check it... it would be better with the same speed 
)
I like it!