I have a 20+ year old STX38 which has been working well with the exception of a problem that cropped up the other week. The PTO for the mower deck would kick in but would disengage after a short period. Upon inspecting the electrical connection to the PTO. I took it to a local shop and he said it was just the wired connection at the PTO. The plastic clip had burned thru and the metal clip itself was damaged from heat. He replaced the clip and connector and when i got it home it worked fine for an hour or 2. Looking at the PTO again I see that it has happened again pretty much identical to before. Any suggestions?