I have my machine mounted in a cabinet at the correct height, (top of bed at 30 inches above the floor), and I use a knee pedal, keeps foot from cramping and shoulders from aching. Recently had a student in early 30's having neck and shoulder pain and when she switched to lower height for pedal, the problem disappeared. Ergonomics do matter for all ages not just us oldies. I am a former back surgery patient so I take frequent breaks which also helps. Good Luck looks like you have lots of suggestions to try.