One application of True Lube Part Number 90349000. This lube helps keep your treadmill operating in top condition. Lubricating your belt at least once a year with True Lube will reduce the stress on mechanical parts like bearings and will reduce the stress on electrical parts like the controller and motor.
Used on the following Models Listed Below.

True Fitness - 
400/1
400HRC
400P
450
450P
500
500 - AOP
500 Classic - 500/1
500 Series - 500ZT
500A HRCO
500Z
540
540Z HRCO
540ZT
550CI
550HRC
550P
TTZ900LC
ZTX - 550 - 120V & 220V
ZTX - 850 - 120V & 220V