Actually, I can repair it. I'm not sure what plastic it's made of, but superglue and plastic primer work well. What I would like is a matching 200mm (8") diameter 45mm wide rear wheel; like the 150mm wheel, these are Walter Barr with 1/2 inch nylon bush bearings. I have other Supaswift spares to swap, including a couple of the later wider ball-bearing wheels and caps