1998 Troy-Bilt 13074 have had for a year runs good and mows good then after 15 minutes mowing pto kicked out after cooling the same thing happened.I looked for problem and found that fuse had melt in the socket and must have been that way for ever.I replaced new socket and 20amp fuse try in engage pto fuse blows.I replaced egnition and pto switch and did not find any bare wires.Where do I go from here.Thank You & God Bless Bob