[ossiblue]

The side of the fuse block where the evidence of overheating occurs is the supply or line side meaning those wire originate at the power source. The red wires at the end of the block probably overheated due to increased resistance at the terminal. I don't have a diagram so I don't know what those two fuses feed, but increased resistance from the load (bottom side of the fuses) will cause heating and it may not be enough to blow the fuse. Add to that a poor contact at the upper terminal and, over a period of time, enough heat can be generated to melt the insulation.

One thing I think I notice. The two terminal screws on the melted wires appear to be zinc coated steel instead of cadium plate--notice the rust on the edge of the slots? They may not be original screws or have lost their plating and, as a result, there could be more corrosion in the terminal that normal. Can someone else chime in on those two screws? Do they look non-factory?