The wheel that is too tight, which side is it? My mystery tight brake was driver's side (USA) .
Now we have the mountings of the wheel cylinders to consider..... The end result must be no wobble, but free sliding movement in the slot. I had to stone burrs off the clips, (the clips tend to dig into the backing plate, and the grooves in the wheel cylinder differ in size). One brake was perfectly smooth in that regard, the other was OK. I could move one with thumb pressure, the other a little tighter.
On to star wheels....yes to clean tooth shape and free moving lubrication. I had to correct the fit of the bores in the wheel cylinder into which the star wheels fit. One was too tight, and I scraped it to fit with a small knife. One was too loose, and the wheel would rock sideways away from the lever. I shimmed it with material from a beverage can, wound carefully into the hole.
I found that my left-rear brake would still drag but was properly adjusted.....if I opened the bleed valve, the wheel would free up. While both wheels are fed from the same offending flex hose, only the left would drag like hell, the right one never did. I never did find out why.
I also learned, after having conquered the Kilimanjaro of self-adjuster problems, that the best solution seems to be: "Dan's Rear Discs".....though a discussion of hub-removal technique is involved.