I learned on my mom's treadle machine. As I remember it, the most difficult thing was trying to go forward. If it went backwards, the thread would break and so you would have to thread it all over again. Then there was always the matter of the leather belt that ran the fly wheel--if it were old, it would rot and break. My poor Mom spent many hours fixing the belt. I guess that is why I can't get excited about buying the old machines!