removing white square glides from window track?

I have two new white nylon square glides for my 72 demon window. These appear to be installed in a lower horizontal metal track but they also appear to be peened over so as to lock them into the track. My new ones seem to have a metal stud of sorts which appear to be a smaller diameter than what I see on the original peened over piece. Am I to assume that in order to change these glides I need to grind off the peened stud and insert my new glide in the track and then somehow peen over the new stud?