Window regulator arm roller query

[rrhorton]

I installed new glass in my '31 coupe and the existing regulators (3 hole) seem to work OK but the roller on the end of the arm that slides in the window glass lower fitting channel binds up. Is this roller supposed to roll against the channel or does it just slide forward and rearward as the arm moves up and down. Seems it would wear considerably if fixed and I cannot get mine to rotate. It is riveted to the arm.