@Going Spare, I'm not too familiar with taking apart model trains so I'll try to give as much information as I can. I managed to solve my derailing issue, the replacement pony truck wasn't screwed in tight enough and now seems capable of making my turns. I applied some WD40 to the wheels but this has seemed to not have worked; where once the tender-driven loco would move without the driver wheels moving, the train now refuses to move, almost if the driver wheels aren't letting the tender move. The wheels are correctly quartered and I'm a little worried to be taking it apart. I forgot to mention that the train has mainly been in storage these 8 years for what's that's worth. Let me know if any of that helps.