It is the armature current that flows through the brushes and the
commutator. Many DC motors have a motor field winding that is isolated from
the armature. This motor requires a current to flow through the field
winding. If no current, or too little current flows through the field, the
motor torque will be greatly reduced, as yours is. Some DC motors have the
field winding wired internally in series with the armature. If not, and the
controller also has a separate motor field current source built into it, it
could be the problem. Some DC motors have permanent magnets and do not have
a field winding and so don't require field current. You said the motor does
not overheat, so that indicates that it is not a loading problem. I guess we
need to know more about your motor and controller to troubleshoot this

Thanks for the help. It is a permanent magnet motor. I see no slipping
of the drive belt and the tread belt surface that it runs on is clean and
quite slick...It just feels like it is a tired motor...I will verify if the
belt
is slipping with some chalk on the belt and pulley may show something.
Oh yeah I am only 175 lbs heavy!
Rob