Thank you for your input. I attempted to reshape the old piece through boiling and cooling processes. It now possesses a rounded form, although the inner diameter measures 24.25mm, which suggests the original rubber band seems lost case.
I plan to handle the Rubber Seal Ring OD22xID18xCS2mm with care. I'm considering utilizing a 10 cent euro coin to gently stretch it to a diameter of 19.75mm using boiling water (or time) before insertion into the original Xbox unit.