I am in the process of changing out the two drive motor to tandem pump hoses on the left side of my Case 1845C. It is an early model with the planetaries. I have read online about the importance of cleanliness, and taken the appropriate precautions. I have been dreading changing these out (I knew the metal cords were showing on the old hoses) because of the horror stories about contaminating this closed loop system. Is there any special advice that anyone can give me in order to help me steer clear of any problems? Blow out the new hoses with air? Is there any need to bleed anything after installing the new hoses? Any other advice? Thanks.