Ok, so I picked these up at a thrift store a while back knowing very little about them. Brought them home and plugged them in and both sub woofers were not working. Carefully opened them up and removed the dust covers. Both sub woofers had bad voice coils. I did some research and replaced both voice coils and the cone and spider on one of them. The other I was able to save. Put them back together and fired them up. They were working but when the volume was to....I don't know ....pretty loud; like 7 the receiver would shut off. I did some more research and replaced all of the caps and checked the control potentiometers for corrosion and excessive wear. Surprisingly, they looked really good so I put them back in, put it all back together and fired them up again. Once again the receiver shut off. I tried them one at a time and even tried a different receiver all with the same result. Can anyone tell me how to fix this problem? Or how to isolate the issue?