Start mining machine?

[hairysammoth]

Spoiler below!

You need to put gas in it too, but the lid on the gas can is rusted shut. Combine the gas can with the hammer to open it, then throw it into the digging machine.

Thanx for your help. I don't see a gas can, do I fetch it from somewhere?

Yes, it's in the same area as the key - in a room blocked off by steam pipes. You need to

Spoiler below!

use a crane to stack boxes to get to an air vent on a "shelf" halfway up the wall (at least, I assume that's what you're meant to do - I made a fancy-pants ramp out of a box and a couple of pallets. Gotta love emergent gameplay!). The gas can is in the room at the far end of the vent.

//edit: Curses, beaten