help! fuel gauge kind of works?

Make sure your ground strap is still on or not rusty giving bad connection.
This is a little metal strap clip located off your fuel tank sender, it spans a short piece of rubber hose, then to the metal fuel line.
If OK, maybe your sender float has leak and sunk. also pull and check sender, make sure the fine rheostat wires have`nt broke.
I`m guessing 74 still uses this system as 67 does.