I removed the lense to clean it. I started with it attached, but it was simply too dirty. I then realized that it came off very easily. This is when I noticed that the gas gauge has almost no resistance to movement. This was mentioned in one of the videos I've recently watched on fixing the "Hummingbird" gas gauge, which mine does.... it vibrates, and has for a long time.
I watched two videos, one where a guy filled the motor with RC car oil, and the other where the motor was replaced. "Stepper motors" going bad are a known thing with the GMT-800s but there aren't any available for the GMT400... and that's because our trucks don't use stepper motors, but "air core motors" according to a video I watched. I found what I need on ebay, and the auction uses both terms, probably so people can find them in they don't know the right terms.
Here's the video on replacement that I watched.
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He has several good videos, although I saw several things I disagreed with on his front disc brake videos. He's very thorough, and his videos kind of remind me of something I might have watched on PBS as a kid... kind of has a Motorweek vibe going on. Maybe it's his voice?
Here is the air core motor I plan on buying
https://www.ebay.com/itm/F-95-96-97...343797095?epid=1188138311&hash=item5675d0ab67
