Thanks all. Spoke to Tecmoto and they want £150 to polish the swing arm but have apparently had a fire so workshops out of commission at present. Didin't think to ask a fitting price but it would appear to be a beeeeg job!
Ziggi: Your bike looks lovely and being a bit of a Magpie I cannot help but be attracted to shiny things so love the rear sprocket carrier etc!
Anyone seen any pics of a Duc with a polished swing arm? Another option perhaps?!