Deere 170 PTO Killing Motor

Hi all. Glad to join as this is my first riding mower in my 51 years of life. lol...Anyway I have a 1990 JD 170 38" cut with a Kawasaki 420v motor. I bought this used and when I first got it it ran ok, but after 3/4 of my entire yard it would shut down. I would let it set and then go back to it and finish. as time has gone on, the cut time is shorter and shorter until now whenever I engage the PTO then motor dies. I have checked that the belts are good, the blades and pullys turn freely, cleaned any residual grass out of the way. On the "firewall" of the mower is a black what I think is a regulator with a plug off the wiring harness plugged in it. I checked and when the PTO kills the motor, this device will burn the fingerprints off your hands. I mean hot as fire. Could this be my culprit? and how would I go about checking before I invest in a new one? there are 2 different inline fuses I can find and they seems to be ok.



Help!

Daddymikey