Playing devils advocate here…(true story)
A job turns to sh@t by a simple sheared off bolt inside a casting.
It was a result of the disassembly of the rear transmission/pto cover.
The JD tractor was stored outside, the fasteners were rusted .
Penetrating oil was applied to the fasteners prior to attempting removal. 9 bolts were removed without much effort, but the 10th bolt sheared off below case height.
Long and short of the story, it took 8 hours to extract the bolt and repair the threads.
The broken bolt was not my fault, but the work was necessary to put the tractor back on line, regardless of what it cost to repair.