Many thanks Uwe
thats interesting information. Pulling the machine apart and matching serial numbers to parts lists I have found a few parts may not be original. One cover plate comes off a 1246 for example. I suppose you can expect that with the age of the machine. I believe the closest match is the 706/47. So far a reasonable number of parts match that version. Therefore I have taken a punt and ordered a 706/47 arm shaft, end bearing, bobbin wheel etc and a bunch of screws to replace the munted ones. Most of the parts were fairly reasonable in price. It’s been an education working on it and fascinating to see the quality of the original build.
thanks again