Hi, I am starting to put together my kit, but finding a little confusion. I ordered the optional carriage mount and I don't understand how it's supposed to be used. I think that the part I have circled in red is the optional carriage mount, but there is this "fork shaped" part indicated by the blue arrow. It seems to be in the way of the 20 20 extrusion that the carriage rides on. Can somebody explain to me what that is for and how it should interact with the extrusion? Many thanks in advance.
