Need help for a problem

OK, I'll be the first to post in this section.
Need some help. 70 GT. Haven't had dash lights in a while, pulled the instrument panel and went through everything. Fixed some chafed wires and rerouted and bad connectors, replaced a fuse and fixed a bad connection/ground and dash lights now work better than they ever had. Not the problem, back story on what I've done. Also replaced battery that wasn't holding a charge, several years old. Here's the problem. Now fuel/temp gage doesn't work. Did before this. All the other gages work, Well, except the clock and it hasn't worked since I got the car years ago. Can see a minute movement on the fuel gage backwards, I think. Didn't mess with those wires but checked them anyway and they are installed right. Reversing the wires does the same thing, minute movement backwards. Applied a couple volts direct to the gage and it works. Pulled and physically checked all the fuses, all good. Have voltage to the gage but still doesn't work. Everything seems to check out. What am I missing?

Raining now but supposed to clear up later in the week and I want to drive the car.

Checked all the grounds at the dash. Applied voltage from an external source straight to the gage and it works. Looks like next is the sender at the fuel tank. Got sidetracked during the week and haven't got on it yet and it miserably hot here now. Caught up with honey-do list today so in the late afternoon tomorrow I'll be back on it. Pulling taillights first to get to the fuel tank. Hopefully that works. Give me a chance to replace the bulbs in the rear sidemarker lights that are burnt out.

Now wonder our wives put up with us and our old cars. They always know where we are. Working on them.

The gauge saga continues. Have power to the gauge. Pulled a tail light to get access to the tank sender and it reads voltage, about what I think it should with the amount of gas in the tank. Reads about 2.5 volts and has about 1/4 tank of gas. Connect everything back up and tried to take a volt read straight off the gauge and it pops the car fuse. Has done this a couple times, every time I try to read straight from the gauge. Even pops the fuse trying to take a reading off the temp gauge. Does this mean the gauge is bad? I can get the needle to move when I disconnect the gauge and apply a small amount of external voltage. Now I will admit when it was working before it would sometimes stick and a tap on the gauge would unstick it. Is the gauge a goner? Now to find one.

FIXED........finally. Went through the whole system again, checking and rechecking all the connections. Found a loose connection at the fuse box. I know I checked that numerous times, don't know how I missed it. The fuel gauge now works. Reassembled the dash and tail lights and checked again. Still works. Even the dash lights work. Which started this whole fiasco in the first place. Now I can take advantage of the nice weather and get it out for some exercise.