Not to worry, I' had go at throwing on a second spring which brought it back so much but still far too high. There is something not right with that linking arm.
Being a prized spanner I have now gone and lost a screwy in the engine which I have just spent a good hour trying to get at to no avail.!!
Thinking that I may as well get another carb, could do with changing the alternator too so may get it all done as one job.
It's a 1641 twin port, what carbs should I be looking at?