Rufus and unconscious Goal are near the junk mine, but there is mine cart missing, so Goal can't be transported any further. A bridge leading to the mine cart stand collapsed so you have to find another way to move Goal. There is a Crane nearby. Try to start it with the Crane Lever. Unfortunately it doesn't work. Check the Maintenance Box only to find Defective Fuse inside. Go to the tunnel visible in a distance.
Notice that there is a lever missing in the Shunting Lever Box to the left. Now examine the mine cart. Unfortunately you can't start it now, but you can examine more carefully its Headlight obtaining Halogen Lamp. You can dig in Junk Heap, but there is nothing interesting there. Go to the right reaching the viaduct.
Notice the skeleton there, hanging on the semaphore. He got a Key on his chest, but it is too high for Rufus. Examine Skeleton and pull off Leg of Skeleton. Take a look at Maintenance Hatch near the semaphore - unfortunately it is closed. Take a Mirror from the post on the right and then open the Signaling Light Base. Take a Signaling Lamp and replace it with the Halogen Lamp. Talk to a strange man named Doc. Use all dialog options. Doc will give you Avial Power Inverter, needed to fix the mine cart. Try to go to the outer turn - unfortunately there is too dark inside.
Try to mount Avial Power Inverter in the Mine Cart. You failed - the device will "jump" into Junk Heap. Dig in there. You'll find spare part which can be used to create 3 such devices! Prepare for yet another mini-game.
Using hints which Doc gave you, combine spare parts with corpuses:
- Emerald Colored Muff on Spherical Corpus
- Screw on Bushing on Spherical Corpus
- Bevel with 4 Spokes on Spherical Corpus
- Cobalt Colored Muff on Conical Corpus
- Clamp Bushing on Conical Corpus
- Bevel with 2 Spokes on Conical Corpus
- Mauve Muff on Edged Corpus
- Push on Bushing on Edged Corpus
- Bevel with 2 Spokes on Edged Corpus
As a result you should have in your inventory Avial, Dorsal and Bi-Nausal Power Inverters. Put one of them into the Mine Cart and then Set Off your vehicle. During the driving Rufus will notice a lever on the ground in a new location.
After a while you'll be back in the tunnel but with some Switch above the cart. Press it to move up.