Hi - Noob here.
 
   My son got a set for Christmas 2019.
   We've used it < 50 times since.
   Yesterday it started acting funny.  He'd put the engine on the track and move it FWD with the controller.
   It would move FWD about an inch or so and then stop and not move again.
   Initially I suspected that the track pieces weren't fully connected, but it happened again after I checked those.
   I then put a multimeter on the tracks - the voltage went up and then to zero -- up and then back to zero -- over and over again.
   I then checked the power supply with the multimeter.  Same thing... voltage - then zero - voltage - then zero ... forever.

   I thinking that the power supply is the problem.

   My question:
        Should the voltage be constant from the power supply?

                            - Mike Pellegrino - Beverly, Mass.  USA
   

Thanks for the 'welcome' and the quick response! 
I'll try getting a new Power Supply and post an update.
     Thank you!
          - Mike