couple of other zerk tips,,,, Sometimes they get painted over and will stick the little ball in the tip up, not letting the grease though. Just scrap off the end. Actually you should always take a rag and clean off the zerk so you don't push new dirt into it while greasing. Another thing that happens is the old grease gets hard inside the zerk and wont take any new grease. Most zerks will unscrew and you can take a small pin and clean out the back side. There are 3 kinds of zerks found on most machines, bolt threaded ones, pipe threaded ones and drive in ones. Just make sure you get the correct one if you have to replace it.