Thank you, gary.
Yeah, it is really hard to understand what the problem is. It seems it's an odd problem. But I might have come up with a solution....
What I did after I wrote my question on the forum, was to down load an Service manual from
www.2manual.com and read the related pages.
I took down the right-hand side where the ink problem set and cleaned everything very carefully. Put the machine together and managed to get it to start. Not directly, but in the end. Then I did a nozzle check and new pen head's attitude. New nozzle check. Now I have managed to print from both reel and sheets in about 2 hours. I keep my fingers crossed that I succeeded and that it was a cleaning needed.
Well I have owned it since 2010 when I bought it from a school. So it has been used quite a lot, but has been well serviced and I have never had a problem before.
Manual was much needed. I can recommend everyone to get one for their own model (They seem to have all brands). It is apparently the same as the service technicians using and it only cost 11 USD.