thanx for that mate i also think it mite be a dodgy fuse coz i took it out and it dont look blown but i put a live tester on the battery side of the fuse and it lit up and the i did the same thing on the other end of the fuse and it did not light up so its there but the fuse looks ok
AGU fuses are forever doing that, don't worry about it. I brought a brand new one like it once

Another 60A should be fine, if not then whack and 80A in there, as long as you are running 4awg?