Window Regulator Roller Rivet Installation—How?

[badpeanut]

My driver's door window regulator won't roll up without binding, so I took it out to either repair or replace. One of the rivets holding the lower nylon roller in place was loose. I drilled it out and tried to install a new rivet and roller. I used a plumbing flaring tool to try to seat the new rivet, but a piece broke out of the new rivet long before it got tight. What is the proper way to seat these?