many thanks for the reply 'grumpy'
here are 2 links to the carbs i found on ebay:

http://www.ebay.com.au/itm/141489910566?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.com.au/itm/1-PC-Law...DefaultDomain_15&hash=item5b0dd4639c

i am sure you have seen these before. the cost is low but i assume you have to get gaskets in addition as well on top of that

the downside is the inevitable 3-4 weeks postage so i may opt to clean the original and see how that goes, i am sure these copies will still be there in a week or so
the original gaskets could be used again but if i can find any locally i'll replace them.
one thing i noticed on the existing carb was a lack of O'ring between the carb body and float bowl, i assume there should be one ?
i guess it has been tinkered with before and omitted for some reason

one other Q i have: is, is there a trick to disconnecting the linkages ?
the carb is mounted on 2 studs, as opposed to the bolts on other examples on youtube, so you dont have the benefit of releasing the carb and manipulating/rotating it to assist disconnecting the linkages. as the plastic parts appear fairly fragile so i dont want to snap them off by forcing them