What is the process for extending a US TR-60 visa at MTT in Thailand?

Went to MTT today to extend (US) TR-60. Arrived at 7:30 AM. Outside the door, Counter K lines were forming with tons of people. Counter J line had only a handful. I asked and was allowed to go in since I was about an hour early. Once inside I was given a queue card and waited to be called to have the paperwork examined. No online appointments were checked. Easy in and out within a hour.

I was not sure where to line up when I arrived so I asked one of interns which one for visa extension. He told me to go to the K line and I said my visa is for Counter J. He asked what my visa is and if it's where I had gone before for the last extension and I said yes and he lead me to the correct line. So if you don't know much Thai, don't just say you're here for an extension and be sure to mention your counter and visa or you might get sent to where you don't belong by mistake.