Fixing a Bachmann Class 25 that won't run properly

My Bachmann Class 25 would not run smoothly, and would not climb hills at all. In this video I dismantle it, diagnose the fault, repair the loco, and test my repair. Table of Contents: 0:00 - Intro 0:27 - Removing the body 1:35 - Removing the bogies 2:58 - Fault Diagnosis 5:10 - Repair 6:45 - Reassembly 8:11 - Testing