eBay Seller Lied About This Big Boy 4-8-8-4 in an Unexpected Way

I found this Rivarossi Big Boy on eBay being sold as a parts or repair project. According to the seller the gears were torn and the locomotive would need a major overhaul to get it up and running again. I suspected the there might have been another common issue causing the gears to perform incorrectly so I ordered it anyway. To my surprise after running the engine on a track test it seemingly worked well despite some electrical bugs. During an overhaul to iron out the electrical, I noticed that one of the gears was in fact not doing it's job correctly due to spinning around the splines. A bit of cleaning and super glue later the model is back better than ever.