Andy, you are wise to ask for help since it seems you may be inexperienced with this. One comment about using headphones to mix: you must test a mix on everything you possibly can, including headphones (cans), speakers (monitors), boombox, iPod, car etc. The 'normal' method is to mix with nearfield monitors, then check using headphones, then test on all other places. The headphones will reveal problems in the stereo field, especially phase cancellation, but headphones ONLY is a bad idea. Let me know if any of these terms or concepts need elaboration.

By the way, as was just mentioned, the ear cups can wear out. I've ordered replacements for my 7506 several times.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.