If you are able tho rest it then I suggest this procedure as I have for all Precors: Sounds like the wax lubrication has finally boiled off the belt, the easiest way eliminate this problem is to rewax the deck. You may purchase this @ http://www.gympart.com/ or call them 1-800-496-7278 I would recommend what is call WAX BLAST they come in 3oz or 6oz bottles.
Now the fun part to apply this product you must first get the treadmill and walk on it for about 5min to heat up the deck, then stop the unit with your product go to upper third of the belt lift edge of the belt stick the nozzle between the belt and deck squeeze the bottle approx. amount 1 tbs of wax to the center then get back on the treadmill and walk for 10 min this is to heat up the wax so that belt will act like a wick to absorb wax! This should be done every 3 months or so. Their a catch if this does fix the problem you may be investing in a new belt and possible and new deck. Hope this take of it!!