Amp making a swishy sound

[Jimb0]

I recently purchased a new tube on eBay. I've tested it on my Crack and it has a very faint swishy sound on the left channel. This sometimes goes away but comes back over some time. Sometimes the swishy sound comes from the right channel as well. I read in your previous post PB that the noise should be coming from both channels at the same time if it is a tube issue. Sometimes it is in both channels but not all the time. I've reflowed most my joints and had the same issue. I've also tried it with different 12AU7's but same issue. Any thoughts on this?

Edit: I'm starting to hear the same noise on my other 6080. It's more like a static sound that I'm hearing but it's very faint. Is this a soldering issue or something else?

[Paul Birkeland]

Do you have the grounding mod in the sticky on this board?  If the tube is NOS and hasn't been heated up in decades, a noise like that may also just go away on its own.

[Jimb0]

Yes I have the grounding mod installed. I wonder if its a soldering issue at the headphone jack which I haven't resoldered yet. It's not a NOS tube but very strong and the seller told me they tested it on different amps before shipping it out but I was skeptical when I wasn't hearing the noise on the other tubes. I'll resolder more joints in the meantime.