1972 polara, Looking for how to remove window roller hardware or where to buy

I have a 1972 polara with the passenger side missing one of the rollers which leaves to swing side to side. I have a 4 door parts car that I want to take the roller from but after getting the front disc to turn it doesn’t feel like it’s getting loose. Is there a specific way to remove them or should I just buy new ones and if so, where?

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Author: 72polarbear