Last time this happened to me, it was due to defective dampers.
If the pump's internal rubber nodes were broken, the ink would just siphon through, and if you had a clog in the line, chances are the suction wouldn't pull enough ink from the heads anyhow. Check for clogs by moving the head aside and make a pull with a syringe from the line connected to the pump responsible for those cap-tops. If the ink drains, then a clog isn't your issue.
If that's the case, it's more than likely that your dampers aren't holding a vacuum, and just letting ink fall out, instead of holding it until a charge shoots it out.
it was the first time 4 me to open my second hand imaki jv130
i said worst thing ill call a the plumber
the pumps sound like tkink o k
found that the line between the caping and the pump was full of dry ink so there was no flouoo of ink between the pump and capping
i removed the capping (even open it just to have a look..closed it white all 8 small springs ..
i cut the tube and try to clean it with no luck this dry ink is like a rock i had no tubes on me..
so i cut some tube frome a differnt color and fix it
pulled the air out
and vowalla! no flud
thank u all