Help! Help! I'm trapped in Seoul Station...

I decided to take a quick trip over to the Lotte Mart grocery store over at Seoul Station this afternoon to pick up some salmon for dinner. It's 3 stops away from Jongno-3 ga station near our apartment, so it should be a short jaunt. I walked over to the entrance nearest our apartment, used my T-Money card (a re-usable card you can load money onto and use on buses, taxis, or subway) to enter, and managed to find the Line 1 track going in the proper direction. The train arrived, I hopped on board, and then, 3 stops later, I hopped off. Everything's going just fine.

Until I tried to exit.

I tapped the card on the T-Money spot. Error 10. I checked the list of errors conveniently provided on the exit kiosk (in English, even). Error 10 = ERROR. Great. I tried again. Still got Error 10.

I headed back towards the center of the labyrinthine station to see if I could find the ticket/information counter with a live person. I found one of the station maps, and noticed that the ticket/information counters all happened to be OUTSIDE of the secure area. In other words, I had to get out to get to the counter. Ok.

So I headed back towards the Seoul Station exit. Tried my card again. Got error 04 -- Card not scanned on entrance. Ok. I think I'm getting somewhere. At least it's not showing me Error 10, the mystery error, any more. Then I notice that I'm not the only person having issues with the exit. I watched a good half dozen folks crawl under the arm when their cards didn't work. Then I noticed a Korean couple where the woman exited, but her husband was still stuck inside because his paper ticket wasn't working. At this point, I resolved that if it still didn't work, I'd just crawl under the arm like the guys did. But I tried again and it still said Error 4. So, I scanned the card as if I was coming in, and it read it. Then waited a second or two, then scanned it on the exit side. Free, free at last!!

Then I went shopping, picked up a few things, ran into a co-worker. Spent about $25 on a single bag of groceries. And headed back to the subway.

Again, no problem entering. But when I got back to Jongno-sam ga and tapped my card, it said Error 02 -- Tap card again. So I tapped card again. Got Error 02 again. So I tapped my card again. Finally, on the third try, it let me out.