Hi Ernie,
after welding the cones in, it had ruined the rubber due to the heat. Also, because the rubber tracks run on these as guides I wanted it to have the freedom to guid rather than the two rubber faces to grip to each other if that makes sense. Also, the later Staman track kit come with the ready made new top track guides rather than distorting the old ones to weld the cones in. These new top track guid come with no rubber, so I copied that.
I hope this helps, and any other questions, please feel free to ask me.
many thanks
Byron Kay, England