Hi it could be a few things
The  motor is drawing to many amps,
 causes could be  running belt to tight /
 running belt/ board needs lubricating 
motor drive belt to tight 
using a long extension leed 
Not enough power to the machine should be  240volts Ac at plug
Motor faulty  the list goes on
                
 hirefitnessequipment@yahoo.com
                
 September 2008