Fuse Box

I pulled the fuse box cover to verify my instruments fuse. One of the fuse leads, labeled as the "Tail Light" fuse partially melted the plastic base and was hot to the touch. I plane to use a digital volt meter to measure the voltage to ground at the fuse point and the current passing through the fuse. I am also planning to change out the fuse box with a new one, which from MSA is approx. $90.00 . Has anyone ever changed the fuse box? If so, how are the conductors terminated? Is is hardwired or through a wiring harness plug?