I got a nice used Bachmann spectrum N scale 2-8-0 consolidation, (first production run), non DCC that runs fine in reverse, but in forwards, the wheels nearly stop rotating at about each quarter turn.

At higher speeds its not so noticable, but still a bit lumpy running.  Clean and lube, or something else?  
I hope its not a return to Bachmann job, because they dont seem too interested in dealing with North American items in Europe.