How do you replace a front pump seal?

I have used a sheet metal screw, either a drill point screw or by first drilling a tiny hole in the seal face. Pulling the screw pulls the seal out. Fun part of that particular seal you are changing is finding a knocker to put the new one in with. The wrong size piece of pipe will cave the seal face and cause it to leak.
One option is to buy 2 seals. Place the second one backward with the knocker pipe inside it. Mark that second seal "Tool" and use it again someday.