I heard the phrase (idiom?)
Weiter machen, weiter machen, nimmer schlacken.
Did I mis-hear it? Or is it possibly an idiom for "keep going, keep going, don't delay"?
Actually, my old dictionary's translation of schlaken is "to form slag", i.e., to form the dross / refuse from the melting of metal. So, it's a reasonable leap to speculate for an idiom.