what the hell does a fuse look like?

[Wrench-Monkey24]

I genuinely have only died on that modifier so far because I can't find the damn thing

[XelNigma]

The glass tube that shows the floor modifiers. It breaks so you have to replace it. Its fairly large but being glass its transparent so its possible you glanced over it and moved on.

There might be more than 1 per floor as well. my 2 man group each found one when only one broke.

[Boboscus]

For me it always spawned inside containers so it`s not that hard to see.