Turn signals not working, blowing fuse
Getting that harness out is not terrible if you are in decent physical shape. You have to release the clips holding the bulkhead connector in place, and snake the pigtail out that goes down into the left kickpanel area. Carefully snake out the far end, the glovebox light, the heater controls, the radio, cigarette lighter connector, etc, and work your way back, the fuse panel, the brake light switch, and turn signal and key switch and headlight connectors,
Frankly at this point it might be a good idea.
BEFORE you do that (if you have not) I would untape from the ammeter down to at least near the bulkhead connector, and to the fuse panel and key switch. You can put temp ties along the way to keep stuff organized. These last areas are the ones with high current and no or poor fuse protection.
Other than that as we have tried to outline, follow the path of the daisy chain wires that go from the fuse that is blowing
If you know FOR CERTAIN which fuse, follow the wire, untape as you go, temporary tie as you go.
LOOK as you go, for hard harness wrap that might indicate "heat," or meltage, and of course shriveled and damaged wrap and wiring.
ALSO remember that this problem may not have started with that circuit. HOT insulation, damaged, melted, may have damaged the wire that is now giving trouble