I just changed the speaker in my champ clone - and I removed, then replaced the tubes to get clearance for the speaker. When I turned it on it had a strong hum. I turned it off, opened it up and looked around. Everything looked OK so I turned it on again. After about 3 seconds POP! It appears that one of the small 25/25 caps exploded. Anyone know what would cause this? I'm guessing that the pins of either the power tube or the rectifier tube were not aligned when I replaced them.