If the blue was cut to short to be useful he could ( depending on the load) could use a jumper from lug on #9 to #6 and put appropriate size fuse in both.
This shows the relay function:
I am guessing that the wires labeled 'RED' and 'Blue' in the diagram above are cut so the 1st 6 fuses are disconnected.
For the new configuration, a wire needs to be connected from "C" to the common line on fuses 1-6 as shown below.
The OP will need to pull the Fuse board out to see the best way to do the jumper.
It is an interesting side note that the reason for two sets of fuses is that the converter has little to no filtering and some devices need cleaner power than the converter could provide.
The remaining Puzel is that the OP said only fuse 7 was working. With the suspected problem. Fuse 8 & 9 should also be working.
Just to be clear: The changes to the wiring for the shunt and adding busbars to clean up the wiring are almost certainly independent of the problem in the fuse box.
From memory the other distribution panel had a positive backplane which was energized by a blue wire from the converter.
Since the user's converter had failed we just removed that blue wire and landed a new positive wire from the new system core and all circuits were energized.