Thanks; I checked and all three wheels are inside their respective V shaped tracks (1 top, 2 bottom.)
When I move it by hand it moves easily on the left side of the unit but has strong resistance on the right side. I can hear what I assume is the top of the carriage sliding against the gray top bar when its on the right side.
When its turned on I hear a rough sound as if it cannot move and the Carriage jerks/ vibrates from the belt being pulled but not moving.