When prepared for shipment, at the factory the weapon was protected by fungus resistant coats over electrical contacts, grease films, and grease packing in the hand operated generator which ignites the propellant. On issue, grease-removing solvents were provided, to be used in readying the weapon for actual firing. This wasn't always understood by troops in combat, especially allies unfamiliar with our approach. When Aussies were issued the 3.5 at the Battle of the Broken Bridge, October '50, they fought off a large group of NK supported by T34 tanks, but had problems igniting the propellants. Funny in retrospect, but not to a guy looking down the barrel of an 85mm cannon.
Little things can make a big difference, in chaos.