A little while ago I posted about a broken curtain track cording thing. Got that sorted after thinking about the possibilities properly. Not wanting the same failure to occur on the other three curtains in the room, I did what I should have done ages ago. I sprayed the track, gliders, rollers, and all with a modest dose of silicone spray.
Immediate improvement in all of them - much easier to draw. And, I think,continuing improvement for a few days after. Quite possibly as it spread further and wider.
Wish I had done it ages ago (and I mean several years) - might have saved the broken roller.