Abstract: During a printing operation, an ink pump assembly is driven in a forward direction by a reversible electric motor to pump ink from a source of ink to an inker apparatus. When the printing operation has been almost completed, the direction of operation of the ink pump assembly is reversed to pump reusable ink back to the source of ink. When most of the reusable ink has been pumped back to the source of ink, a valve is actuated to direct the output from the reverse operating ink pump assembly to a waste material receiver. Once the ink has been pumped from the inker apparatus, a valve is actuated to connect the ink pump assembly in fluid communication with a source of clean-up fluid. The clean-up fluid is then pumped from the source to the inker apparatus by forward operation of the ink pump assembly. Once sufficient clean-up fluid has been conducted to the inker apparatus, the ink pump assembly is again connected with the waste material receiver.