Just measured the one I have, Honda part number 45450-126-000 and its 110cm or there about.
Can be brought new here
http://www.davidsilverspares.co.uk/part ... 450126000/ or from here
http://www.cmsnl.com/products/45450-126 ... 450098671/
Maybe ebay if you get lucky.
Not sure what you mean by the brass bit, if it's the nipple end then most bike shops can repair this.
The speedo is driven from a gear in the front wheel hub, remove the cable from the speedo, spin the wheel and see if the cable spins, it's completely mechnical.