HP CLJ 4600 - Printing fine but have a toner leak problem? Toner leaks can be a very messy problem, but what could be causing it and what to do? The HP 4600 has been known for this issue and the magenta cartridge is usually the culprit. The problem used to be due to the long cleaning cycles originally set via the DC Controller (RG5-6391). HP has since revised the controller, shortening the cleaning cycle to prevent the overflow of the waste reservoir. The DC controller revision must be a 6D or higher. This can be determined by viewing a configuration page under printer information > printer number. The versions run 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 (alphanumeric) If however, the DC controller has been changed and the problem still persists, the next plan of action for most techs is to change the High voltage power supply. As a side-note: We have found it is almost always that the toner cartridge itself (even if OEM), can have this symptom and would need to be replaced. *This Tech Tip is contributed by Laser Pros. Visit their website www.LaserPros.com or email any question to marketing@laserpros.com.