The deck is probably cracked or bent. the deck is made of particle board or hardboard, and with the pressure from constant pounding they can bend or break. On a Proform it´s probably only 3/8¨ or so thick and it´s easy to break this. With a proform as it will likely be outside of warranty the part will probably cost upwards of $200 plus labour to install. Essentially it´ll probably cost more than the machine is worth. If buying in the future, consider Vision or Matrix b/c they make their own parts so they are cheaper when it comes to replacing a part. If you´ve actually used the proform treadmill to the point of breaking the deck I would suggest buying a higher grade treadmill. Proform is made by Icon Fitness and they make Reebok, weslo, and more. All essentially the same crap, with a different label. Try True, Vision, Life Fitness, Precor, Sportsart, Landice, Startrac or other quality treadmill. On these top end units, you may have the option to flip the deck to extend the life of the treadmill. Cybex makes a treadmill with a plywood deck that can be flipped and rotated for 4 wear surfaces and this will extend the life of the treadmill, part of the value of the unit. Also I would suggest to stay away from Bowflex. The name was bought out by Nautilus and they took old Schwinn treadmills and rebranded them Bowflex. They are still not great quality units.
Marlene Evans
May 2009