Plastic white roller too thick

Hi

I have a casement window which was part truth 40055 right side. The one fits but the white plastic roller that goes under the window piece is too thick and I cannot fit it into it. (The piece that you mention in picture that is 9/16") The old style is a single metal platen and without any rubber and it is really thin. How can I adjust it so it fits or do you have any other surface mount operator that can fit? I am looking for 9.5" arm.