Look at Wal-Mart, in the chain saws and supplies; they have the exact device needed, probably with the "Oregan" brand name (used to lube the nose tip of a chain-saw). It's a push-type gun with a cone-shaped metal tip; you hold the tip against the little openings on the hinges and push on the end of the gun against the hinge.
The gun is even labeled "Made in Germany". It's about 6 inches long, clear plastic, with the grease in it. Hope this helps you.