Need help after storage room

[blackwolf]

The storage room in Lead Shaft B that is

Spoiler below!

I found the key and the gas can, yet I can't find where to use them. Is it in somewhere in the Auxiliary Shaft? It's barricaded and I get in there. If not, where is it?

nm: found the answer. Although now I'm stuck again. After the mining machine

Spoiler below!

I got into the area where that big slug blasted through the door. There's a door with no handle that can't be opened, a huge pit, and after running through some spider caves, a room with a desk, and a lever that I can't move up or down. I don't see what else to do.

nm: got the lever to work.