looking for some advice. we have a 2013 supreme executive and the grey plastic infill for the rubber window seal has shrunk due the effects of the sun. i am looking for anyone who can supply this. it is 23mm wide with a slight concave/convex shape. it is referred to as either plastic insert or infill. I can find the infill for the outside corner runners but not for the inside windows, it quite a soft plastic but supreme were no real help and the Victorian supplier of the window ceased manufacter in 2015. Any help appreciated