Alemite gun

[Mad Mac]

I think I recall someone on this forum recommending using an Alemite grease gun for filling Model A steering boxes and diffs with that heavy oil which doesn't pour easily. Today I tried using an Alemite gun (see pic) to fill my steering box but without success. Even when I dismantled the nozzle and removed the ball-bearing and spring (why are they there?) I still had no luck. No matter how hard I push on the handle nothing comes out and pushing the spring-loaded stalk/nozzle in and out still doesn't work. What am I doing wrong?