I also sew on hardwood floors. I think I have tried everything. The only thing that worked for me was a piece of wood. One machine is in a SewEZI cabinet, positioned next to my dining room table, so basically out in the middle of the room. I put a thin strip of wood, almost the exact size & shape of a hardware store wooden yardstick, against the legs of the table, then butted the pedal against that.
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I have another machine that's against the wall and I have a piece of masonite between the wall and the pedal. You have to check the thickness of whatever you use because some things may keep the pedal from fully operating.