Manley Amp is humming - troubleshoot :(

Hello all ...I have been chasing a gremlin on the left side of my system for about a year . Last night my Left side was completely distorted at lower volume and after that just turned into loud humming....

Manley Snappers
Manley Jumbo Shrimp Pre amp
Klark Teknik DN360 EQ
Source was Macbook Pro

So i switched the amps to see if the hum would follow the amp & it did ....even with everything off except amp... super loud low end hum a grounding issue...changed all tubes 3 times , still hums ...any clues before I send it in?

thanks !

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Yikes! Other than a quick peak inside. You’ll probably see something..

UNPLUG first, remove the valves and flip it over..

Just be careful, don’t be touching things if you don’t know how to discharge the caps.. LOL Can get a little noisy.. discharging sometimes..

LOOK.. you’ll see something wrong I bet.. Maybe something loose.

A wooden dowel is easy to use and see if things are tight.. Be careful with pencils graphite is very conductive.. LOL fun to watch though..

Doesn’t cost to look..

Most common problems can be found by careful visual observation.  Look at all of the electrolytic caps to see if there is any bulging (most evident at the caps on the end of the capacitor) or leaking.  You can tell if they are bulging by comparing them visually with others.  Look to see if any resistors look like they have heat damage (looks dark or singed).  Sometimes a resistor will vaporize and simply not be there--you will see only the leads of the resistor left on the board or in the circuit.  

If you are lucky, and a bit handy, you can replace parts yourself.  As someone mentioned above, discharge capacitors before sticking anything conductive (particularly your fingers) into the amp.  Anything more and you are best off sending it to a technician.  The good thing about tube gear is that almost anything is repairable.
thanks for the help! I opened it up , didnt seeing any glaring issues , I'll check more closely...
I assume it still hums with all inputs (sources) disconnected? If so, then I'd suspect a capacitor in the preamp and will need service. Unless you feel comfortable, I would have a professional tech look at it.
It hums w preamp disconnected , it’s definitely the amp , thanks 
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OP, I thought you said you switched amps? tvad, think you nailed it.
I did switch and the problem followed the amp to the right side from left ...thanks 
Could also be bad output transformer,
Oh, you switched channels not amplifiers. Output transformer is a possibility, but FAR less likely than a cap.
Could it be a ground loop hum?

best way to check?

pretty sure it's the amp , love to solve this w/o sending to Manley...
Are you good with a soldering iron? Look for any capacitors that are bulging or leaking. A thorough visual examination of all components and solder joints before doing anything.
You better have the necessary skills before going into that amp, you could make a bad situation worse.
yes agreed


  Im good with soldering iron , I didn't see anything upon first inspection that looked suspect...might take another look
I use a magnifying glass now. Also freeze spray is a good way to find a problematic component or at least section, good luck.
I looked it over just now , there's one cap under a bridge that looks a little smashed in , but nothing bloated , looks like Im gonna have to send it in ... 🙁
sent to Manley....apparently it was the Caps on the top of amp, replaced all 8 on both sides ...I'm hoping this quells the noisy issues...Jumbo Shrimp preamp still suspect though....pulled off the lid and moved the middle circuit board and it was Cracklin' Rosie once... 😕