I have had many 'chugging' engines in the past, most were used though. I don't think I have had a C-12 new out of the box though and the ones I have now don't do the chug. Why not return it to Amazon since their Returns are so easy and see what another one does. For the most part, if my memory isn't leaving me, I think all of the ones I had that ended up chugging were the Thomas Type motors which I think the C-12's run with.
BTW: welcome to you and your son to BluePlasticTracks Darth 😃
BTW: welcome to you and your son to BluePlasticTracks Darth 😃
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