My mom has a newer mower.<br />2002 Cub Cadet riding tractor/ the smaller one.<br />It has hydralic transmission.<br />When blades are engaged this loud unbalanced sound comes from the bottom left side..<br />Not from blades..<br />But either the engaged main pully or left pully that runs the blade. Not really to sure, but not hte right side of the mower..<br />Now I have changed both tensioners, becuase they were bouncing around really bad and one was bad to begin with, the spline had spripped. <br />It has been sitting at a repair shop for 2 months and they have put new blades on it which I told them it was not the problem.<br />It was proven also... Yesturday when I stopped by to find out why this is taking so long..I made the guy show me the old blades. He had them in the garbage can. He dug them out and told him he better put them back with our mower.. There was absolutely nothing wrong with those blades.. I personally watched the guy in town sharpen and balance them..<br />Is it a possibility it is main pully problem in the motor where it engages to the drive that turns the pully to operate the belt?.. It sounds long and I hope I said that right..<br />At a glance you really can't see any ware from the main shaft or pully, when it is turning, but you can see the tensioner bobbing around alittle and hear that rumbling sound coming from the left side. It is really not good... Do you have any useful answers or help..<br />Thanks for your time..