My skin crawls when I look at the stock wiring. There are 3 or 4 wires under each terminal how do you know which wire could be bad. When I had my car down for restore I completely rewired the fuses. I put in a terminal block with 30 spots every wire has its own test point. And a updated fuse block with 16 instead of 12 fuses. The best diagrams I found were at Dave Hillmans 912 web page.
Wiring Diagram for Early 912
Good luck