why is the whole thing covered in some sort of oil that's kinda sticky? Hmm.. I think the first thing I'll do is wash the whole thing, dismantle the whole motor on top and then see what to do from there.
btw how do I drain the thing? I think I hear water inside. hahahaha
there must be a drain plug at the bottom of the tank. check what material is it as somes with copper plug which deforms easily when u grip using pliers to loosen them. Dont be too happy screwing it all the way out if there is pressure in the tank as u will end up looking for the drain plug. I bet when u loosen the drain plug a bit, nothing will come out as gunk has blocked the opening. u will need to unscrew slowly or use a cloth to cover it and watch leech like substance flow out then suddenly a spray of either water or gunk mess up your floor.
Wash it but dont dismantle first. Since yours is electric driven too then dont be too happy when washing it with water.
After washing, remove the air fitting and soak them in degreaser or petrol or diesel and cleaned them. Re install and see if it works.
If it does works them fill the tank up, check for air leak if any. If no air leak then search for oil leak. The whole thing should not be covered in oil if there is normal oil leak unless the tank is not drained for some time and the air oulet is clogged causing it to spray air mixed with oil all over the place.