how to get rid of mildew smell from front-loading washing machine

I have this musky smell coming from a front loading LG washing machine no matter how much I cleaned the drum and I would leave the door open so it air out. I'll start off by acknowledging I did NOT read the manual (I take full responsibility for this so I really don't need a lecture lol) and thus have never drained the pump and suspect previous owners didn't, because it had this stench when I took possession. I finally read the manual and realized I was supposed to be draining and cleaning the pump/filter at least once a month so you can imagine the wretched smell when I did. I spent several hours cleaning until the water ran clear - used a tooth brush and long drain brush with bleach. I ran the machine on clean twice, once with bleach. I've used vinegar and tea tree oil. I have ran 3 loads of laundry and while the clothes don't smell, there's still a mildew-y smell from the machine. I should mention that when I drain the water from the pump it's clear and does not smell - the smell is from the drum itself. After a load I spray the drum and door with a mixture of water, vinegar and tea tree oil and wipe down...the smell is gone but when I go back and check the next day it smells again. I've followed all the steps on this site except the inlet filter: https://www.lg.com/us/support/product-h ... aintenance

Is there anything that I can do eradicate the smell for good or is the damage irreversible?