Ivory is very dense bone like material...it is usualy very resistant and flexible even in thin scales...but...it all depends on the condition the ivory is in.

If it has cracks around the pin tightening it with a ball point hammer must be done with great care. I recomend openi g the razor so that the thicker part of the wedge shaped tang can support the end of the scales in case of wnwanted pressure on the end of the scales or a missed hammer blow....

If the scales have an even colour all the way with no cracks arround the pin or chips that may promote a crack you can proceed with light ball poi t hammer taps in a circular motion on the pivot pin...take your time and do this with the blade opened.

Ivory is usualy non porous so that means oil does not get in it to stain it...but suprisingly warm water tends to rehidrate the colagen in the bone matrix...making it a bit more flexible...this may help before pining