My HP plotter was leaving skip marks on every set of plans for a month, and I was about to order a $90 replacement kit. My coworker said to try isopropyl alcohol and a stiff card instead, which felt too simple to work. One pass over the heads and the lines came out crisp again, saved me real money and a trip to the supply house. Has anyone else had luck reviving old hardware instead of swapping parts, or is there a line you won't cross to keep gear alive?