At last I have sourced the knurling wheels. In putting them on I have upset the (very complicated) set up for adjusting the wheels.
the instructions for use are here
http://industrieprodukte.swarovskioptik.com/en/gb2_infos-news-information
But there are no isntructions for setting it up.
I have two problems , the screw in the side of the main body (arrowed) is stuck and has a narrow shallow slot.
once I get it out I am not sure how to reassemble it so the rotating the adjuster nut works with the cams on the knurling wheel sleeve.