Power Tube/Output Transformer Hum?

[kerobit]

UPDATE: after reading what was posted and going through and checking the B+ it seems like they may have originally had the 6v6 going to the wrong filter cap. I moved it to a different one and now the hum is gone!

The only issue remaining with the amp is theres a little bit of a ghost fizz in the background behind clean notes if anyones got any ideas on that. I've got new tubes/caps in it.
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Hi, first time posting so hopefully I'm doing this right.

I've been working on an amp build thats similar to a champ in layout other than a reverb/tremolo added. I noticed with some 6v6 tubes I get a hum that comes on during startup, then stays while the amp is in use. I haven't noticed a pattern which 6v6 cause the issue (all known good tubes). I threw it on the scope and have included a video of whats going on.

I've also done the chopstick test and the wiring position/etc does not appear to make a difference.

The hum also stays the same no matter where the volume is set. EQ/etc does not effect it either. Ive pulled the preamp tubes and its still there as well. I tested the pin going into the 6v6 and the noise doesnt appear to be there either, so somethings either happening with it, or the output transformer?

Just wondering if anyones got any thoughts/ideas.

[tubeswell]

The hum also stays the same no matter where the volume is set.

Not enough filtering, and/or Ground loop hum

[Willabe]

So it's a single ended (1x 6V6) amp with reverb and trem?

Not enough filtering, and/or Ground loop hum.

Did you add an extra B+ filter node before the normal 1st B+ filter node?

Here's a link on grounding;

http://www.valvewizard.co.uk/Grounding.html

Do you have a working schematic you can post?

Can you post pics of the amps inside guts and a pic of the amps chassis top side, PT/OT/choke/tube sockets? 
 

[kerobit]

Its a bit of a mess. Its my first time and its built on the remains of an old Pepco amp. I dont have a schematic but its basically a Champ with an added reverb from a princeton reverb and a tremolo from a Beltone amp. I added a ground bus and a star ground as well. Its odd since it goes away if I use a different 6v6.

UPDATE: after reading what was posted and going through and checking the B+ it seems like they may have originally had the 6v6 going to the wrong filter cap. I moved it to a different one and now the hum is gone!

The only issue remaining with the amp is theres a little bit of a ghost fizz in the background behind clean notes if anyones got any ideas on that. I've got new tubes/caps in it.