yes check nozzle check first and show it us by photo ( not a thumbnail please
).
test print from the user menu key panel top right and the one below it together gives nozzle check from the head. Yellow might not be so clear on the picture....... but other will certainly be.
I am struggling with flexi 8.1 rip too with lines although less obvious.
Even with calibrated custom colorprofiles.
With Onyx rip it is not there.
let us know the outcome.......
For service manual use this link
www.jupacreations.com/RH38_S_MANUAL.pdf
Cheers, Paco