Hi all, I'm having this same problem. I thought my 2 speed pump went bad since it wouldn't turn on at all (only a hum). Replaced both capacitors and it still didn't work, so I bought another pump. I just installed it and now it kicks on low, but when I change it to high, the low speed jets stay on, but then I just hear a hum. Any ideas? It's a Sundance Optima 850 if that helps.