IF you have a leak under the E-57/58 Motor, and you remove the Motor to see what is going on, and see this, you need a new Gear Pump.As the Ger Pump wears internally, it allows pressure up under the Pump Shaft Seal, and it pops the Seal out. You can press it back in, or even change it, and.... it pops back out again. There is no fix other than replacing the Ger Pump. It is a pretty common occurrence once a unit is a few years old. Sometimes they last 4 years, sometimes 10 years. The point is that it is not unheard of.