If I read correctly, the black prints, and then it fades off. Is that correct?
if so, you most likely have not done something correctly attaching the captop, damper or have not used a good quality damper, captop. in my opinion the only dampers and captops that work properly are genuine Roland parts. All of the third-party parts have always failed when customers purchase them. I always end up putting in genuine Roland parts.
when you say you check the ink slots, what exactly are you doing to check them? And what errors are you getting?