This is a link to the drawing which might help you.
I wanted to replace mine because some of the hinges were broken (they are on the inside - don't look because I broke another one when I looked) . I was advised of this by the Service Assistance. Apparently I had placed something heavy on it. If I did it would have been a suitcase once or twice. Why else would you have the sill if you can't actually use it. Owners beware. Do not sit or put anything heavy on the sill! This part is actually not fit for purpose.