Horizon Fitness CST3.5X Treadmill Horizon Fitness Updated September 21, 2021 23:00 For the 2007 Horizon Fitness CST3.5X Owner's Guide, please click here. For the 2007 Horizon Fitness CST3.5X Exploded Diagram, please click here. Was this article helpful? Yes No 0 out of 0 found this helpful Have more questions? Submit a request Related articles Horizon Fitness CST3.5 Treadmill How to Replace the Running Belt and Deck on a Treadmill. How to Fix a Treadmill that is Stopping and Starting Horizon Fitness 5.3T Treadmill Horizon Fitness CST3.6 Treadmill Comments 0 comments Please sign in to leave a comment.