251 Pump Clutch idler arm pulley.
Those help alot. I've had the 251K for about 6 years so I've replaced hydro hoses, belts and other things over time. It's used to mow an acre once a week at my get away house, so it's not where I can work on it everyday.
I really would like to see a pdf of the service manual as to the replacement of the Pump Clutch idler arm pulley. I can't see how to get in there and replace it. Pretty sure it's the problem.