jb77

I have an sub10 subwoofer I received from my boss. He hardly ever used it but it did work for him. Now it doesn't work. I took the circuit board off and I don't see anything leaking or swelling. I did notice a plastic receptor with two metal prongs sticking up. It looks like something is missing. I circled it in the photo. Can anyone comment on this? The power indicator light lights up and I have tried other audio cables with the sub. When I crank the power all the way up, I get no hum, no sound at all. Thanks.