I just bought a Thomas the Tank Engine set with the EZ Track.  It started working out fine, but now the Thomas locomotive keeps stalling along the track.  I have tightened the connectors and checked if there are any gaps.  I see nothing that should be causing the stalling.  Now, most of the time the locomotive doesn't even run.  I tested other locomotives and they all stall; and I've confirmed they work on other tracks.  Please help.  Thanks in advance.