4880 works just fine until the printer does one of its random “quick cleanings,” which immediately starves most of the channels of their ink. (I’m using your ink.) The local authorized repair shop has replaced the pump & cap, and all 8 dampers. By doing a “light cleaning” and then letting it sit for about 15 minutes, the channels seem to clear. The technician said the only other thing to replace is the print head. If the print head is actually bad, why does it work sometimes and not others? Why would the dampers not refill after the automatic “quick clean” it does sometimes before starting a normal print job?