Exmark LZ PTO disengages when brake is released

Hi,, need help with my 2004 LZ27KC724. I can engage the pto with the brake on but as soon as I release the break the pto disengages. I've disconnected the seat safety switch and tried jumping the wire. The brake switch seems to work correctly ( mower won't start if not on, shuts off if break on and handles are pulled in, etc) I've check for wire damage..

What next??

They put relays in there to stop people disconnecting the seat switch.
The entire safety circuit is an earth one so any place a wire contacts the mower frame it will kill the engine.

OK,, an update,, as of now it's working. Here's the joke. On the clutch switch there was a jumper from the start control to the clutch control, but what do I know?? I have no experience with this stuff.. But after testing the brake switch and a few others, and getting dizzy going over the schematics that jump just didn't make sense, but the mower had worked for years, so I kept looking, gave up and cut that jumper.. The mower works, so now I don't know if a different switch or relay quit working or one that didn't has started to...