I have the same problem. I haven't been able to mess with it. I would start checking the ribbon cables and fuses.
Yes.....please do let us know if that solves your problem, it may help others down the road.Thanks for your reply.
I kept looking around this site & found mention of American Screen Supply supporting Tjets. Their tech thinks that somehow we've shorted out the printhead ribbon cable. It may have gotten water (or ink) on it & shorted out the cable. We've ordered the cables (not expensive) & we'll see what happens when we replace them.