Higher output guitar pickups have the opposite effect of lowering the volume to reduce gain. Higher output increases distortion. You can use a boost pedal to push the amp harder too.
You're still not listening about setting up a useful test scenario. Guitar at 100% volume, amp NOT
at 100% volume. Amp should be 30 to 50% volume during testing. Turning the amp up to 100% isn't going to do anything for you except increase the likelihood of having issues. Do your testing at 30 to 50%, get it good, THEN crank it to 100% to see what's left that might need to be cleaned up. By 50% you should have plenty of dirt.
Here's a thought: let's say your tubes were all fine. But since somebody is stubborn about listening to people trying to help him, he keeps his amp at 100% all the time for testing, pushing the tubes beyond any reasonable safe zone. What if there are issues with the amp or voltage, or external issues that can negatively impact the health of those tubes? Pushing everything beyond reason in the test environment isn't the best way to troubleshoot or diagnose any issues. That's what QC does AFTER the product is completed.
What I said about getting the front end correct (input resistor and grid stoppers) is to help block noise and radio interference. You clearly have an issue with this. You might want to also invest in a filtered inlet (like the Schaffner FN9262-10-06), or a filtered power strip (like the Furman SS6B).
I appreciate your enthusiasm, but this is where patience might be more effective.