all to make it easier for the carpet guy to carpet the stairs.

I'm not exactly sure what you mean by "filter piece" though. Mine had a simple dowel connection at the bottom and spacers at the top under the handrail (no hard fasteners on the spindles at all, as they were just kept in place by the dowel at the bottom and the spacers at the top).. oooh, maybe you meant "filler" piece?

anyway, my son broke one being dumb. that helped me understand how they were installed. It definitely helped that the one he broke was the top stair. Again, at least for my situation, those little 'filler' pieces snapped loose relatively easily with a tap hammer and chisel/screwdriver (only a couple of dabs of glue held them in place).. as each piece was removed the downhill spindle was easily lifted off it's dowel and also removed. there were a couple spaces that made me worry they might split, but they didn't. regardless, I would suggest being more methodical about it than forceful, just in case.

one thing of note, since I did all of the spindles in my scenarios, I made sure to number the pieces and the spindles because there tends to be even slight variances in length. Iow, I made sure all the parts went back to their original spots.