Update: Well it looks like I had a solder issue in the end, I finally found a few hours with a mate to re-solder most points, as this was my first solder job ever there was allot of residual flux in my soldering.
It looks like it was a dodgy solder on either the potentiometer or RCA connector and now I don't have any more recessed sounds. WOOHOO.
I do have two more questions, if I push down slightly on the potentiometer there is allot of crackling when adjusting the volume. Should that happen?
When I turn on the Crack, the 6080 has a purple illuminated gas within the tube, and then settles down - around that time there is some crackly noises. Is that normal? Here is a video of what I am seeing around the 16 second mark of the video - . The video was made after the 6080 has warmed up so it doesn't last long, but initially the bright purple gas lasted about 5 to 10 seconds.
Thanks in advance.