Roto logo stamped in SS track - black component for L and R casement windows

Show is the intact track assembly for the left casement window. The entire SS assembly, including the black part is 10 5/8" long. Unfortunately the right casement window is not operable because the black part is broken. Think the black part may be called a "shoe". It is not sliding, but is fixed and retains the lower SS arm, seen below the coated operating arms. I need the parts necessary to replace the black component only, if that is possible, but if it is part of the track assembly that is okay, too. Can you assist?