Gaining access to the area with the cable car | Laboratory Walkthrough Resident Evil Zero HD Guide

Sterilizing Agent is the most important item to find in this room.

Enter the room unlocked using Green Leech Charm (M4,16). Move forward a bit and eliminate the two zombies on the ground (one of them will be crawling towards Rebecca). You can now search the area. The most important object here is the Sterilizing Agent lying by the wall. After obtaining this item, leave this room.

With the new chemical, go back to the central room on level B1, where you interacted with the red tank before (M4,12). Approach the gas chamber shown in the screen above. Stand near the control panel, open the inventory and use Sterilizing Agent. You will remove the gas from the chamber. Go inside (M4,17), eliminate the zombie on the ground, turn around and prepare to be attacked by a zombie which was sitting by the wall. After killing the monsters, take the Breeding Rm. Key.

The place where you should use the key from the chamber.

Take the eastern door that lead to the main corridor on this level (M4,10). You can use the key that you've just obtained to open the eastern door. Before you enter the small room (M4,18), make sure that Rebecca has grenade launcher set as her default weapon (it is best to use acid rounds, but napalm rounds will do as well), or as a last resort - shotgun.

Locate the Dial after you eliminate the hunters.

When you find yourself in a new room, slowly go forward. There are two hunters hiding behind the corner. You can attack the monsters right away or move back after noticing them and wait until they head towards the hero. When you win the fight, check if Rebecca needs healing and search the room. Here you will find the B.O.W. Report file and additionally the Dial near one of the cages.

Now, go back to the room on the level where the service lift is (M4,13). Interact with the lift and place the Dial inside. When you send it up, switch to Billy (M4,8) and collect the item from the lift. As Billy, return to the main corridor on level B2 (the one in which the leech zombie was) (M4,7). Use the door shown in the picture above.

Rotate the dial so that it shows the number from the combination (in this example number 4) and select OK.

Open the inventory and select "Use" on the Dial to put it into the mechanism. Now you have to choose the right combination. You will find hints on the Leech Growth Records document. The combination is 4863. Every time, you have to first rotate the dial (left or right - it doesn't matter) so that the red arrow points to the right number (the first one is number 4). Then, you have to select "OK". Do this with all the four numbers to open the door (M4,19).