Complex sentence: Indeed, Harpers had denied him an advance, and since he was already in debt to them for almost $700 he was forced to borrow money and to arrange for the typesetting and plating himself.
Split into simpler sentences: Indeed, Harpers had denied him an advance, since he was already in debt to them for almost $700. He was forced to borrow money and to arrange for the typesetting and plating himself.