How would you explain this thick layer of slime otherwise? It's the amplifier fuse (actually the fuse to protect the car when the wiring to the amplifier is inadvertently shorted somewhere). I had issues with the amplifier (driving front speakers and sub, headunit driving rear speakers), cutting out for minutes/hours whenever the wife was singing along. It worked perfectly whenever I had the car . A smart ghost... After searching I eventually found the fuse hanging in water next to the reasonably new battery. Battery well with battery removed: So I assumed I had somehow plugged up the drainhole when making fitment for the larger battery. But there IS no drainhole. As there is no water supposed to be there... so I guess I have a leak somewhere as discussed in some other threads. There is a grommet that I removed which drained the water. But I needed loads of water and a sponge to get the goo out. I'll leave the grommet out for now, but I'll try to find the leak when I find the time... The fuse AFTER quite some cleaning.
Wow, that looks terrible! I think you need to cut off and replace those connectors, they don't look competent, consider the advanced corrosion. Perhaps you can get salvage components. Could the leak be from above? Any accident history, maybe something not resealed correctly.
I put in a different fuse-holder, so that part is covered. (cut off 20cm of off the amplifier-end and replaced the part from battery to fuse completely, the advantage of having such stuff lying around). I am worried about the leak, but given the number of threads about this, it is not that uncommon, so should be manageable. No previous accidents afaik and I have had the car for 5 years without any previous leaks.