I bought the 4020 set the year it was released.  We played with it for a number of years and had no problems.  A couple of years ago - when I still got Playmobil wholesale - i bought a new charger and a new battery.  Somehow, I have ended up with 2 of these sets  

 but I  cannot seem to get either one working.  Do any of you train buffs out there have any knowledge of usual causes for the trains to stop working - other than the battery or charger.  The light comes on the charger when I plug it in and I checked the battery - it has juice.  Put fresh batteries in both controllers but not getting movement from either train. Is there anything specific I can do in terms of narrowing down the problem and possibly fixing it?  I know its hard to speculate but I figured someone out there may be able to give me direction!!!!
Thanks
Annie