Sliding Mirror roller

Hello,
We have a 1968 sliding mirror and would like to identify and buy replacement rollers for it. The mirror itself is two panels, each 30"W x 36"H.
The rollers, two per panel, are approx. 3/4"L x 1/4"W x 9/16"H (see pictures).
The roller assemblies are just pressed into the bottom of the mirror panels.
When the panels are rolled, there is a noise as if the rollers are out of round. Can you please help?

Thank you very much for your time.