help with HP FB750

[Jonathan_54]

hello, let me tell you,
I work with some HP FB750, and lately I have had problems in one of them with the black color, now every time I print the black color some blue lines appear,
this only happens when it is printed in express mode, in indoor mode looks good, at first I thought it would be solved by doing air purges in performance, it works but after a few minutes the lines reappear, then I try to do the maintenance of clean the printhead and the same thing works for a moment and the next it doesn't, and doing a jet mapping doesn't work in express mode, which is what I'm looking for,
I leave a photo and any help is welcome.

 

[CMYKENGINEERING]

Several reasons could be. Meniscus settings, the air filter could be clogged on the black line, or the printhead's rubber gaskets are too old and can't hold the system hermetical.

 

[LarryB]

When we had an FB500 we would never print solid colored background in Express mode as you would get banding.