Aluminum wire isn't as bad as some would have you believe,if it's properly installed.

I doubt they will set the place on fire if the proper cover is reinstalled but I see hot spots that will soon leave you without power. I also see a red and a black wire at top right that are double lugged and I wonder if those wires are fused. Since you already have hot spots with burnt insulation and corrosion on wires,you need an electrician to look at it asap. Guessing at electrical problems based on one poorly lit picture isn't something you should ask people to do.

I'll answer your questions in a moment.

First I have to warn you that those 30 amp plug fuses "protecting" what appears to be AWG 14 wire are a VERY serious hazard. You're risking fire.

I'm also worried about those extra wires connected to the RANGE fuses' terminals. They look like they might be AWG 10, which is good for 30 amps. I'll wager that the range fuses are 40 or 50 amp. Let me guess, those go to an electric water heater?

Your installation is severely inadequate for modern needs. This is a DANGEROUS situation. You should have it upgraded as soon as you can possibly afford to do so. Take out a loan if necessary. This is urgent.

TODAY, replace those 30 amp fuses with ones appropriate for the wiring connected to them. If in doubt, put in 15 amp fuses. If the smaller fuses blow, remove loads until they don't.

Now for your questions.

The aluminum wire that caused problems was AWG 12 and AWG 10 solid.
Large gauge stranded wire is not a hazard as long as anti-oxidant
compound was used when it was installed.

What you have may not be
aluminum, however. The bare neutral that looks like AL might be tinned
copper. The hot wires look to me like oxidized copper. I'd have to
see it in person to be sure.

The slight projection of the MAIN fuseholder might be caused by dirt or
debris behind it. Those holders have blades the push into slots. A
little less than full engagement probably won't hurt.

I missed the burn marks on the MAIN red wire that Klem noticed. That's a bad sign. Thanks to Klem for pointing that out.

This whole installation is dangerous and needs to be replaced immediately. If this is your main panel, you'll most likely need a complete new service including weatherhead, meter pan, and main panel.

If this is a subpanel (and another more modern one is the main), you'll need a new panel and new cable from the main.

Please take care of this is soon as you can. And get those 30 amp plug fuses out NOW!

Agree with geoffrey. That fuse box was outdated and should have been replaced in 1960. Aluminum wires are excellent. Aluminum wire connections are the problem. When you have dissimilar metals, like aluminum wires connecting to copper wires or clamps, then the two metals literally eat at each other. As the parts eat away they go from being tightly connected to loosely connected and then disconnected. As the connection weakens the risk of overheating, arcing, and fire increases. You really, REALLY need to get that box out of your house.

It appears that the original poster may no longer be monitoring the responses.

The wiring coming into the box could be aluminum, but I have also seen a lot of older copper wire that has been tinned, which gives it a silver color. This wiring usually also has a very fragile fabric covering that may flake off if the wiring is flexed. The old wiring should be completely replaced, and disturbed as little as possible until its replaced.

The two new black and red wires on the top are also a really bad idea, since they appear to be connected to the unfused side of the box. Do they have some other overcurrent protection?

Bruce

It's been exactly one day so hopefully the OP will come back to check in. People get busy. I sure hope she does though...this sounds bad.

Bruce, I'm pretty sure you're right. That looks like tinned copper to me. The insulation might be OK on the range cable (top right), but the main doesn't look so good.

Unfortunately on these old cables, the rubber insulation under the cloth braid tends to harden with heat (as here) and air pollution, so yes, it can flake off.

The panel is a typical one that would have served an entire house when it was installed, probably in the 1940s, and possibly earlier. The main fuses (cartridge type, on the left in the pull-out) are probably 60 amp, since it has a range pull-out.

Being an old-house person, I've seen a lot of this kind of stuff. :(

As for those double-lugged wires at top right, they're not unfused, but they're almost certainly not fused adequately. They're "protected" by the range fuses, but not at the right ampacity for the wires or the appliance they supply. Good chance it's a water heater added within the last 30 years or so.

This is definitely unsafe, especially with all those 30 amp plug fuses on what looks like 14.

Yea, thats the problem with fuse boxes, people shove whatever fuse they have available in there, so it needs a 15 amp fuse all they have is a 30, good idea! Not.

Also, if you hear any popping or feel any heat it needs immediate action. The fuse box is on its last life, and they dont last forever. Wear over the years causes the contacts to go bad. Need a new panel, and they should change out the meter and new wire between meter and panel as well while they are at it.

A good electrician will talk with your poco and discuss meter change out at the time of panel replacement.

"people shove whatever fuse they have available in there ..."

I'm sure there's some of that, but more often, when a 15 amp fuse opens repeatedly, they "upgrade" to 20 amp. When that opens too, they go to 30 amp. All the plug fuses from 5 amp to 30 amp fit in the same pre-Fustat Edison base fuse holder, so what's the big deal? :(

When Edison base fuse boxes were common, so were electrical fires from overheated wiring. They seemed to happen more in the
winter, when people plugged their extra space heaters into those
over-fused circuits. In the medium-size town where I lived, every January and February the newspaper carried stores about families left homeless by electrical fires.
I'm an old-house fan, and I
don't think I've ever seen a plug-fuse panel in an old house that didn't have at least
one over-fused circuit. Thank goodness for circuit breakers, which pretty well eliminate this hazard (although I'm sure a few dunces actually swap out breakers that trip for larger ones).

That fuse box - You can't make chicken salad out of chicken sh*t. Wait till the place burns down. Hope they have smoke alarms.