Hi everyone. Sorry to keep bugging you with my message requests. But I'm really into POA!

Anyway, I am so totally stuck in the sandstone caverns.

1) I understand that I need to do that mine cart trick again, but I'm not sure I'm doing it right. When I'm here:

You come to a railway junction. The main rail line continues north to south, and a side track leads off to the west. The main railway passes ten feet over a pathway leading west and east from here. To the north is the second chasm along the central railway. To the south, you can see yet another barrier placed across the tracks. At the side of the railway, you see a switch box to change the mine cart's course between the south and west rails.

Am I supposed to jump off the railway? If I do, it says:

You flip the switch box lever to divert the course to the southern route. Then you jump off the mine cart, and it continues along the railway, disappearing from sight. You listen for a few seconds and hear the mine cart crash into the barrier. Then you hear more crashing sounds, as the mine cart derails and falls down the slope to the side of the track.

Is that right? I can't see any other place to do it - I have to head south, and if I jump off earlier, I die.

2) If what I'm doing in part 1 is right, how do I find the mine cart? Are there time constraints like last time?

3) I got the boulders off the trapped miner, but I understand I'm supposed to get something from him while he's recovering from his injury in bed. But I checked the patient ward of the hospital, along with every single quarters in the Coriolis, and I can't find the guy again. Where is he?

4) This doesn't have to do with the mines, but...I got permission to go into the HEEC, but I can't get past that broken door. How do I get into there?

If it helps, my inventory is:


3 Nanoxite Stones
Scrap of Paper
Silver Key
Metal Rod
Matches

5 Peryolitium Shards
I.D. Card
Gold Key
Pickaxe
Washcloth

Leather Briefcase
Passcard (CQ20024)
Peryolitium Key
Wrench
Round Pot

Metal Briefcase
Passcard (CQ30021)
Vault Key
Noise Filter Headset
Small Mirror

Employment Papers
Passcard (CQ60537)
Dragon Key
Knife
Sleeping Pills

ISO Access Form
Supply Room Card
Crowbar
ISO Energy Pulse Gun
Rock

Violations Report
Mine Access Card
Light Tube
Tranquilizer Gun
Tranquilizer Spray

Beetle Analysis Papers
OSA Card
Radio Receiver
Military Uniform

Peryolitium Shell Diagrams
Izacladia Access Card
Fire Extinguisher
ISO Officer's Cap

ISO Accident Report
Business Card
Crank
Pet Snacks

Sorry for this long post, but I need direction. Thanks to anyone who'll help me!