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He means what was the matter with it before you caused the hum.
Here is a good way to isolate the hum: unplug one and only one at a time the audio tubes before the output and see which stop the hum and which don't. For instance if the one before it stops the hum then that stage is not at fault, but if it does not then look for a problem in the components between it and the output.
Don't tweak the adjustable coils unless you can confirm via proper troubleshooting that they are at fault if you walk them too far away from correct when they are not the trouble you will only give your self needless headaches down the road.
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