I contacted Gravely Tech. Evidently this is something that has never happened before. Tech rep gave me a very long list of things to check. I then got with my dealer. They went through the machine with a fine tooth comb. It took two weeks to do this.
Luckily I have an extremely good dealer & they resolved the situation to my satisfaction.
Is it a whistling type noise? If so, it's the fuel system venting.
That is perfectly normal.
My Gravely Pro Turn 260 is in my storage shed. I can be in there and it will whistle for a short period and stop. Later, it will repeat the same sound. The newer emission regulations require a different setup than the old days.
The second video is that sound.
Of course the machine did not duplicate the electronic noises while in the shop. All electricals checked out as good. No loose wires, corroded connectors, or burnt/discolored fuses. No shorted circuits were found & the ECU showed to be fine.
They did change out the factory Duracell battery because they have had problems with those batteries in the past.