Hi all, So my son got couple of used engines (Blue Highlander and Flying Scotsman) and tracks from one of his aunts. They were boxed and in mint condition. We set up everything but the engines do not run smoothly. They start, slow down, then pick up, slow down, pick up round the tracks. The engines are also running at high speed even with a slight turn of the controller and it is impossible to run the trains slow. I tried both engines, and the issue remains. We got two old style transformer/plugs and the issue persists with both of them. What exactly are we doing wrong? Any help would be appreciated. Thanks.