The blade on the mower deck stopped while cutting grass. I have replaced the PTO switch and clutch. Tractor started up and blades were working. After cutting 100 yards blades stopped again. Assume I have a bad wire some where. Any ideas as to where and what to check??

Hi,
Assuming you got the clutch and its stay( on the left side and should be able to rattle the clutch back and forth) done correctly; the two most common places are the wires from the clutch (right side front and must be kept out of harms way) and the rear wiring harness (right side behind the rear wheel/tire.)
Peace,
Clarke