Sorry been out of town at meetings this week. You still have not said which pressure they have checked. Who is working on this? are they experienced or backyard mechanics? The charge pump is internal so the only thing they can do to verify it is OK is check charge pressure in neutral and while trying to drive forward and reverse. Then check pressure at the forward and reverse servo piston covers while trying to travel forward and reverse. Please don't just jump to the conclusion you have to split the tractor.
It is rare that a hydrostatic drive would fail instantaneously unless something like the clutch or input shaft failed.
It is rare that a hydrostatic drive would fail instantaneously unless something like the clutch or input shaft failed.