what i have learned from seiko is that the error means the sensor located on the corner of the print carriage (small black box below green lever) cannot sense that the media is present. the sensor might be dirty, so i cleaned that and the black strip that runs next to the platen. that sensor is supposed to see the edge of the media (in this case a mesh banner) against the black strip. apparently the sensor checks for the media every 2 meters. as a cheat, i'm placing a piece of white tape on the black strip, right under the media edge. i will shortly see if that helps. if it's not that, then it could be a worn bearing, or worse, L/R motor failure.
so, if anyone has anything else to suggest, feel free....i have already lost 35 feet of mesh banner on this....
i placed a small piece of white tape on the black strip, lining up with the edge of my mesh banner. i successfully ran my 20-ft banner.
this was the first time i ran something this big. it seems that if the material skews even a millimeter, when the sensor looks at the edge of the mesh--which isn't straight like paper--it simply doesn't see the media is there, and flushes the job.
I did two, for me necessary things, first taped the sensor and second updated the new firmware, which doesn't stop when skew is detected but rather continues with print if you confirm it.
i had the error again even with my little piece of tape, so i must have an intermittent mechanical problem. how can it work if the sensor is taped over? doesn't the printer need to be able to see the edge of the material?
i would say that the carriage sensor does need to see the media at set periods. saying that i've also used the tape trick and never had any problems, but this was on media that seemed to skew badly, as it was worn on the core poorly. even if the media does skew by 2-3mm the printer should keep going, as the latest firmware just returns a warning and asks if you want to carry on.