A Bad Day in the Lab

Below is a photo of a High Energy Ball Mill and photos of a High Energy Ball Mill after a catastrophic failure.  In this instance an O-ring failure allowed ethanol to leak out of a grinding jar which then ignited inside the mill causing an explosion.  What went wrong?  Unsuitable solvents were previously used, degrading the O-ring and a lack of scheduled service allowed a degraded O-ring to be used.  The solution is to read the manual, follow the instructions, and include a preventive maintenance schedule when using equipment.