Capacitor Help

My Definitive Technology Subwoofer developed a loud hum. I looked online and saw that replacing the capacitors might fix it. My capacitors are not budging which, I understand, can indicate they are bad. There is no voltage written on the capacitors. The only thing written on them is: Bennic, Bi-Polar, 220 mfd, Vent, -40c + 85c. Can anyone help me find a replacement?