JoAnn, the machine may run well without them, but those capacitors control and keep down interference. My son says if you can find the value of the capacitors, they should be replaced with equivalent new capacitors rated at least 600 volts. The modern capacitors are made of better material and are smaller in physical size. You should save the spaghetti insulation tubing that is on the leads of the capacitors. My son is a vintage audio equipment collector and all of the radios he has have capacitors and they're a "waiting timebomb". Unlike sewing machines, he has a power supply that is adjustable and he brings the voltage up on his radios gradually to keep the capacitors from blowing up. Your machine may run fine without them, but it can interfere with your television and/or radio reception. Okay, I'm repeating the lecture I just received from my son! His hobby, since he was in his early teens, has been electronics, especially old tube radios, amplifiers, etc. It's also what he studied in college, so he has learned a lot over the years.
Jeanette