Thanks I did find one. I had written off that site as a scam but it came though when I waited.
I'm not sure how the serial numbers work. This manual states it is good for machines from M/C No. 337 001
My machine has the following numbers on the right side of the frame:
4719071
and
14BN2045/3469617/LD/000529/M
I think it is a 1985? 1400B.
The biggest difference I see in the manual is the integrated shuttle and gear box, whereas mine has a velvet drive shuttle and a seperate JCB gearbox. Also, one master cylinder reservoir vs two (on mine). The electrical diagrams as they are, definitely help.
Thanks