I have an old (40+yrs at least) Magic Chef gas stove. It still works well but the burner control knobs are becoming very hard to turn on and off. How do I lubricate them? What should I use (and not use)? I don't want to use the wrong thing and ruin the appliance.

This is usually caused by years of oil and grease buildup that hardens. Turn the gas off at the appliance or at the main. Lift the top of the range and using a very light weight oil or WD40, lubricate where the control shaft goes into the control. Let it sit for a few minutes and then start opening and closing the control. It should smooth out. Once you are satisfied, turn the gas back on.