In Yu-Gi-Oh 5Ds Stardust Accelerator how to get your Duel Runner back

Here is a non-spoiler walkthrough created by Samurai Bandit from GameFAQs: http://www.gamefaqs.com/portable/ds/file/955057/56440
You'll probably want to start at the section called "Getting Back what they took from you", which explains how to get pass the guards (Ctrl+F to look for it quickly).
Good luck.