I found this useful video about adjusting the push rod[You must be registered and logged in to see this link.]
and you can buy the push rod pin assembly for £22.50[You must be registered and logged in to see this link.]
The downside is that none of the replacement pins include the bit that actuates a switch on the clutch lever assembly (presumably a safety cut out) [You must be registered and logged in to see this image.]
as you can see in this photo.
BTW Thanks to tip about the 1.5mm allen keyed grub screw I successfully removed the assembly from the broken lever. Without heat or force.Put it into my new cheap lever and it fits like a glove. The build quality and weight look similar to the original lever. Under £14 for the whole the job. JOY!
PS The metal on the original lever around the pivot was nearly worn out (if you look closely on the photo above). So perhaps it was a lucky break.