I bought a singer 600 Auto stitch sew machine, where is on off switch? It looks in good condition, but can't find on/off switch. FEEL REALLY STUPID

Look for your machine's free manual here: https://www.manualslib.com/s/singer+600+autostitch.html

I have an older Brother that has no on/off switch except for the light. Just plugs into the wall--step on the foot pedal!

I have a vintage Singer 500 and there isn't power switch on it as well. I unplug it when not in use. Plug it in and if it powers up, mark the top of the plug with a dab of white-out so you know which direction the plug needs to be for connecting to the power source. If it does not work with the first attempt, flip the plug over and try again.

Because of grounded wiring in modern houses, the old plugs may only work when they are correctly positioned.