Hello, I bought a good old 1960 Farmall 560 to do work around the property. First tractor. Love it. I brushhogged using the PTO for a year or two, and box bladed dirt around all summer. Now, I can't get the PTO to mow again. The driveshaft turns the mower blades but has no real torque. The blades stop when you actually start cutting even though the tractor is running. It is like the PTO disks are not engaging. The PTO shiifter shaft is missing the handle so I don't think it ever was disengaged. The shiftershaft moves a little but I never feel it lock in like a standard transmission gear would. The driveshaft turns free when the tractor is off. I took the IPTO off. It is a wet clutch disk type. There is no visible damage. What are options? Thanks.