SP540V won't print black

[J Hill Designs]

One problem remaining is when printing solid dark colors there are light streaks running parallel to the feed direction, (perpendicular to the carriage travel), at 12 - 21 - 30 and 39 inches across the print whenusing bi-directional printing.

if its only in bidi mode, then its probably chromatic banding - clean the encoder strip, and double check bidi alignment.

if its uni and bi, then it could be heat causing tunneling in between the pinch rollers.

 

[Vinyldog]

I do suspect the encoder strip. I have cleaned and flipped it. It was also flipped back in 2013 so basically I just put it back where it was then, but am just trying things.
I would like to replace the strip but I think the machine has to be recalibrated after replacing and I'm not sure what that involves.

 

[Vinyldog]

status report

So an update for anyone interested: The cleaning cartridges seem to have worked for awhile but Black once again has completely stopped printing. And once again all three other colors are printing beautiful. Nozzle check looks great except for black which does not print at all.
So this time I tried replacing the O-ring around the black ink tube where it connects to the damper. The original ring did appear to be worn and there was a healthy crimp in the tube, so I cut that part off. I also pulled black ink through with the syringe and I noticed the plunger used about half the travel before any ink started coming through.
I also have noticed that the black cartridge has smudges around the port where the needle connects so I’m going to see once again if I can notice any anomalies in the line and where it connects.
I am beginning to believe that the head will have to be replaced, however I am going to exhaust every other possibility first.