My last two postings here mentioned the problem I've had with the LLK ink channel. To summarize, for several months, going back to the middle of summer (2018), each time I've awakened the 7900 and run a nozzle check the LLK channel's pattern has been partly to completely missing. Nearly every time a simple "standard" cleaning of the Y/LLK pair has cleared the problem and I've been able to print with the usual excellent results. I worried that this might be indicating my printer was nearing the end of its life, now that it's more than seven years old.
Several weeks ago I did an experiment that seemed to solve the problem. I've waited this long to report here so I'd have time to complete a number of print jobs and gain more confidence that the problem really is fixed. I now believe it is.
As mentioned in my last posting, I'd replaced the LLK ink cartridge, which had about 20% of its ink remaining, with a new one; that didn't help. A while back I stumbled across Marrutt USA's Web site and found a section about using "purge files" to clear stubborn clogs (which may or may not really be nozzle clogs). Each purge file is a jpeg of a single color patch corresponding to one of the printer's color channels. I downloaded their files for the 7900, but didn't have an immediate use for them. I revisited their site and found they'd changed the files a bit, making the color patch a bit larger, so I once again grabbed the files.
I then set up by waking the printer and sending the LLK purge file. I did not print a nozzle check prior to this. The file puts a LLK patch in the middle of a sheet of paper (I used plain bond paper). I then ran a nozzle check and it was perfect.
In the weeks since then I've printed a number of jobs both for clients and of my own work. Various papers, various print sizes. As usual prior to each job I've run a nozzle check, and each time LLK has been perfect. There have sometimes been little nits missing from other channels, requiring a cleaning to include that channel. Pretty normal behavior. But LLK has been perfect every time. I can probably remove the question mark from this posting's title!
You can get these files here, and I'm grateful to Marrutt USA for making these available.
--Jay
