Cant help on the pic but often the stiffness is down to the movement at the carb end. Lube it up well with spray of your choice.
thanks ghostbiker that was a help, my choke now works, the cable was also partly at fault as there was a slight kink in it, I bought a pattern cable off eBay which is a good fit but the nipple on the carb end is slightly smaller and where I had a replaceable nipple on another cable the nipple twists slightly which is another job.
So what is that extra bit in the photo?
Just get it ivanised, you won't ever need to use your choke after that.
If you look on the carbs the choke cable pulls a bar which in turn pulls 4 little brass plungers (one on each carb). Each plunger is protected with a little rubber seal, pull it back with a little pick and lube the plunger with some oil and replace the seal. I did this with mine while i had the carbs off to fit an Ivan's kit and the choke is perfect, light and smooth to operate. You should be able to do this with the carbs in-situ.
Jim.
I managed to squirt some penetrating fluid in the general direction of the choke plungers, which does seem to have worked, the cable was stiff and needed changing.