sorry for the delay in replying
i measured the diameter of the bush and its about 0.20 over size, the shaft is around 0.15 down.
there is also a lot of sideways play on the gear, i can get a 30 thou feeler guage between the gear and the 20 mm spacer and this removes a lot of the wobble in the gear. i may have to get or manufacture some new spacers.
i did some investigating into the bush itself and they look very similar to a wrapped bush
http://www.bowman.co.uk/products/wrapped_bronze_bearingsif you look at ashimoto's pic you can just see the line where the bearing is split at the top right,
steve at 400 four bits has got a gear in stock so im going to e-mail him and see what he wants for it and i will also find out a bit more info on the bushes themselves
Russ