The angle lever cam is case hardened, not hardened throughout. i.e. hard on the outside to resist wear, softer on the inside to allow for adjustment. Similar to Lindy, I use a lead mallet to adjust it.
I did come across a Phelps angle lever cam that was over hardened, and one moderate tap with the lead hammer and it snapped in two.......but never had a problem adjusting a Star angle lever cam.
Bruce