hey I have a model 917.255913 I replaced the drive belt with a 1/2x93 belt from advance auto and it worked to mow half the yard then I smelled belt burning turned off machine and looked the belt jumped the flat idler by the engine it was running in between the v idler and the flat idler my mower didn't have a belt on it to look at when I got it I might have had belt on wrong I had it around the engine then back of belt on flat idler running back to movable idler by clutch around clutch then trans then back to engine one question the movable idler by the clutch how do you adjust it I tried it different places but didn't help but don't know the right way to go about adjusting it my older one I had didn't have a adjustable idler please help the belts are 25 bucks a pop here in Morgantown wv at advance auto napa wanted 40 for the same size belt but I guess it might be heavy duty
this is a pic of the belt I bought and broke lol thanks Jason