I have a common 16s Elgin (model 291, 7j). The 4th wheel has a broken pinion. I have a spare pinion. I removed the broken pinion and was ready to stake the new one on to the wheel. I stopped. I have never done this. Am I using the right punch, I asked myself. I was about to use a flat hole punch then thought maybe I should use a rounded hole punch. I lean towards the flat hole punch (that is to stake the pinion to the wheel) but thought I'd ask here. Which punch should I use?