My new 71 Dart and the issues I am finding. Help needed please

Speedo cable- be sure the cable is not bad before you lube it. Is more common for the cable to be bad. Fuses- use a test light. Do you have juice going into the fuse and out. No juice into the fuse means you have a problem farther up stream. Check these things first and then move on to others. Fuel gauge- remove sender wire at gas tank and ground it, this should peg the gauge needle to full, if it doesn't we can talk about what to do next.