I don't know much about the Gravely.
But some models have a device called a eye-q.
Seems to monitor the current on the pto.
All notes at Gravely refer to a eye-q manual which I can't access.
But I would bet either one of the devices replaced are defective or the wiring harness has a problem.
This could be a big deal to track down.
Meaning jump out the seat switch and or brake switch. Not just at the switch but where it terminates at the other end of the wiring harness.
More than likely I would start at the seat circuit. Since the unit starts fine and only has a problem when the brake is released or the pto is engaged.
Last edited by Ruben Rocha; 06-18-2010 at 05:52 PM.