Do the disconnect first. Leave it off the battery for a night. If you have a battery tender or the like place your battery on it after cleaning the terminals. Before pulling the sending unit i would remove the dashboard from the tank (three hex
bolts, two at the top near the tree and one at the bottom of the dash board). Carefully remove the dash board as it is attached to the wiring harness by two connection points/plugs. Disconnect these two plugs to completely remove the dashboard. Disconnect the green plug tucked under the tank at your seat. You should lift the tank at the seat to do this.
Clean all the connections with electronic cleaning solvent that is plastic friendly. Watch out not to spray on your paint. Clean them again...
A little dielectric grease on the connections in morning and reassemble.
If nothing changes.... then there are lots here who will help some more.