Hello Jaxs...
Yes we did try some starting fluid, per local Kubota shops recommendation. Amount was very minimal, and there was no noticable 'explosion', it actually made the engine seem more resistant to 'trying' to start. The engine cranking sound and behavior remained unchanged before and after the starting fluid exercise.
No gasoline or additives were added to fuel. Some fuel was drawn to check for water, no water.
New fuel in the tank.
This pic shows the pick tool I was able to send through the hole in one of the pistons. There was no resistance at all poking it down in there...
pick through piston
Regarding the 'ran a week ago', I was misunderstood the 'last time it ran' information. My brother primarily uses this tractor, and the real timeline is that it ran fine, then sat covered for a few months (through winter) and then would not start. The last time it actually ran was in October 2023. Tried to start it early Jan 2024, and have been trying to troubleshoot and start since then.
The property is under camera surveillance, and is a few miles out of town, and at the end of the road. It's highly unlikely that someone messed with it.
I suppose the starting fluid theory could explain the similarity of the damage between the two pistons, if that is a thin spot in the part design, then it would probably fail in the same fashion...