When my feed tube stops up, I hold the tip against my other hand and mash the pedal. It forces the air back down the tube and clears the feed tube out. That may not work if you have a gun with the trigger on the gun instead of a foot pedal.
Same here, but when you find yourself fighting a block every few seconds, it's time to find the culprit. Most often it's a bigger chunk of media or hardware that slipped through the grate into the hopper. A piece or two of screen stapled to a wooden "window" makes a great cheap sifter.
