Thanks for your help with the parts order Archie!

Regarding the operation of the clutch. I would regard mine as normal, and fine for me.
I gave the bike a strip down and major service when I got it. This included dripping WD 40 in the clutch cable till it ran out the bottom of the cable. Cable routing was fine. The clutch lever was worn and loose. The wear was on the opposite side of the plastic washer at the pivot point. De-greased, sanded, Pratley Steel, sanded, greased. I also applied grease to the inner cable at both ends.
There is a huge difference in my and Straatkat's 610's clutch action. I wouldn't even bother with a hydraulic unit! (We have discussed this before.)