Proform 350s crosstrainer treadmill; surges 3 MPH to 4MPH

Walking Belt is Worn: The only certain way to test for a worn walking belt is to take a DC amp draw (if you have a DC treadmill) or an AC draw (for AC). Trying to look at the belt or a feel test is highly unreliable. Better tests, if you lack a DC ammeter (they are expensive for a good one), are a coast test or an incline test. The coast test is to get on the treadmill as the lowest incline setting and walk on the treadmill at 3 MPH. Pull the safety key and it should take you 2-3 full steps to stop (this is a general rule…some like a few Tunturi models stop on a dime even with a healthy belt but for most models, this tests works well upon). Fewer steps indicate high friction. The incline test is to put the treadmill at max incline and walk on it at 3 MPH. If the treadmill operates normally at max incline but bogs down at minimum incline, replace the walking belt. Gravity takes over for the drive system eliminating much of the friction problem. On some heavily worn walking belts, this test will not eliminate the problem. Go to your local hard ware store and purchase silicone spray. Apply Lubricant by lift one side of the running belt spray contents length wise starting at motor shroud to the back end repeat this process on the other side. If this unit bogs down again then you will have replace the running belt and possibly the deck