I’ve been having troubles with the VM channel on a 7900. The behavior that I have noticed is that nozzles fail in large chunks (several strips at a time), always starting from the bottom and than progressing to the top, and multiple successive cleanings (cl1, cl2 and cl3), slowly regain the nozzles first at the top and slowly toward the bottom. Last time the full channel failed, and I needed to perform so many cleanings that I finished 70% of a 150mm ink tank to regain all nozzles (again I regained the nozzles first at the top and than slowly toward the bottom, with the bottom part being disproportionately harder to regain, with many Cl2 cleanings often doing nothing).
The printer prints flawlessly for a few days and than the bottom half of the VM nozzle drops again. All other channels have not had a clog in months.
Also, now after performing by mistake a cl2 cleaning on “all” channels I am starting to have a few dropped nozzles at the bottom of LK, which are quite harder to clean than usual (this is one of the channels that before cleaning had been clogless for months??).
Can piezoflush help or is this a sign of a failing head?