Thanks for posting and sharing both the video on replacing the belt as well as for the quick release knobs for removing the plastic covers on the deck!
I just ordered some for mine!
Maybe try to modify...and replace the existing float with a cork type style?....see if that makes the difference?
Good luck!
If not then......
https://www.lawnmowerforum.com/threads/hustler-raptor-flip-up-fuel-gauge.40136/