We always kept the threads for the e-tool (it's "
entrenching" tool) screw-sleeve locking mechanism 'dry' - we'd clean them with hot water, dry them, lube them with our weapon lube (the white, goopy stuff) and then wipe the threads 'dry' (as with the bolt of an M-16) to prevent the accumulation of dirt or sand or rust or locking up in extreme cold weather.
MOO, the intermediate e-tools like yours (wooden handle w/spade and pick) were the best - the older models didn't have the pick and the newer all metal or mixed metal/plastic didn't offer the same 'heft' when digging or chopping. But that's just personal preference on my part and experience with all three types.
From what I can tell in your pics, it looks as if you need to take a file to the edge of your e-tool and sharpen it some as with any shovel. Some basic maintenance goes a long way in having a good tool like that one - and a clean, sharpened (but not like a knife blade), and lightly lubricated shovel makes for a much better tool.
Richard