Help with gas tank ground wiring (gas gauge troubleshooting)

[JUST JOHN]

So I traced my in-opp gas gauge to a bad ground at the sender/tank. After cutting up my newly caulked hatch for access to test, welp. I jumped the ground and saw my gas gauge at 'F' for the first time in almost two years. It worked intermittently before last season.

The gauge and sender check out per the procedures outlined here:
https://www.jamestowndistributors.co..._Reference.pdf

My question is with regards to the ground wiring on my '77 OB Seafari 20:




Does the front ground wire just go to the filler flange? Or...?

As you can see there is only one wire on the sender and it grounds to the tank via screws. There is however a tab on the sender flange that I'm thinking may benefit from an additional ground wire... Thoughts? Where would I run it to?

I traced the rear two (power/ground) wires to the rear battery compartment... Ideally I'd replace all these old wires if I can trace them all down. Any recommendations? Please confirm where these wires go... I ran out of daylight and it's a little crowded in there w/ the oil tank, battery, and water separator under the rear starboard seat hatch. I'm sure the + wire runs up the starboard side loom to the gauge. If I can do this in stages so I can get the floor buttoned back up soon, all the better.

This thread had good relevant information regarding grounding:
http://www.classicseacraft.com/commu...ht=tank+ground

Any help or guidance would be greatly appreciated.