Hi Luke,
For the Tom Senior parts, Have you tried the "Tom Senior Yahoo group" ?
https://groups.yahoo.com/neo/groups/tom_senior/info

Also, Is it a metric or Imperial machine ?
If it is metric, it would be fairly easy to make a replacement from something like that:
http://www.ebay.co.uk/itm/TR-20x4-D-...item2a4f371064

For Hand-wheels:
http://www.ebay.co.uk/itm/402291-Mac...item43becaedcd

I know, it wouldn't be original... But at least you'll be able to play with them !!! :-)

RNR