I have an SB-220 and C4 is overheating. The original one had started smoking and was bulging on one end. I replaced it with a new Sprague of the same value. I plugged the amp in and kept an eye on the new cap. I noticed that within a couple of minutes, the cap was getting quite warm, so I turned the amp back off. A visual inspection isn't revealing anything obvious. Can someone point me in the right direction? Thanks.