Our bike pump, a $26 planet bike "st" model, stopped working recently. It would take four pumps to accomplish one normal pump's worth of pumping. I figured I would try greasing the gasket:
No change. Then I listened to where air was coming out during a pump and discovered this threaded plastic gasket near the base had come loose. All I had to do was tighten it and the bike pump was working good as new again.