Hi Peter,
I have been stopped on this since Friday as I have trigger finger on my left hand and it triggered. I finally saw a doctor yesterday afternoon and he gave me a cortisone injection, that has freed it up but it is still rather painful.
I have had a look at the Jet lathe as I think the blade holders on them will fit the Parkside, if so I will purchase a set. I can also get a handle/thumb screw thingy that can be pressed on to the head of a capscrew and that will eliminate the need for a grub screw and allen key. So many possibilities 
I still have not checked the alignment of the top and bottom arms and as it is raining again I will leave the shed until later.
While I am at the top and bottom arms I will have a look at reducing the stroke of the blade, with luck the eccentric may already be drilled, if not it should be a simple job.
As I write the rain has stopped and the sun has come out so maybe off to the shed after a quick cuppa.