taking the cartridge off and inspecting it under a microscope revealed that the diamond was displaced in the cantilever (in comparison to my 17d's) on this particular cantilever the diamond appeared to have been set into an open ended slot and that most of the diamond was sticking out of the back with hardly any of the tip showing.
@pcutter1
This is my 17DS mkII under a macro lens, I have no idea how anyone can re-tip it, very bad idea!