I bought a 72" Rogue about 2 months ago.  So far i have about 17 hours on the engine.  After breaking a drive belt early on i realized i needed to check the belt tension each time before i mow.  Every time i check the deck belt the tension is off.  I've adjusted it to the point i have no threads left on the adjustment.  Would i be better off switching to a Kevlar belt and what could make it stretch this much?