OK so it's been a few years since I've played seriously and my guitar care has definitely slipped.

I have a fair bit of tarnishing (no rust just really dull) on my tuner heads and I wanted to clean them back as well as I could
I heard WD-40 is a good way to remove the buildup so I decided to remove the heads completely and clean them away from the rest of the guitar but when trying to remove the heads after removing the screw from the back and the nut from the front the washer and assembly are still firmly attached to the head.

Anyone know if this is because they are glued down or have recommendations for removing them?