Nautilus T618 Service Manual page 167

17. Using a #2 Phillips screwdriver, remove the 2 indicated screws from
the MCB Cover and remove it.
18. Be sure to observe the distance from the Speed Sensor to the Drive
Pulley. This distance affects the performance of the Speed Sensor, and
can easily be shifted accidentally during replacement procedures.
19. Make the Drive Belt come off of the Drive Pulley by rolling it in a
counter-clockwise motion.
Keep fingers out of any pinch opportunities when turning the
Pulleys.
Speed Sensor
MCB Cover
167
Drive Belt
Drive Pulley
Speed
Sensor