If that doesn't work, then the gauge head itself can be dry of lube. I have made up a fixture before to use on motorcycle and car that uses rubber hose and grease gun to clamp onto the outside of the gauge unit and when sealed you carefully pump a SMALL amount of grease in to lube the bushing right at end of gauge. Done correctly the gauge will go to working perfect and for years.
If you pump in too much to foul the flyball magnet you have screwed up. Just a LITTLE.
Quick way to test if the gauge? Grab the input stem that sticks out and spin it by flipping it with fingers while watching needle, if the needle moves jerky the head bushing is dry.