epson 4900 4 channel stop printing

[laci]

Hi all so we use an epson 4900 with refill carts 2 weeks ago at end of the day i tun a nozzle check and i seen pk and vlm channel have some missing lines so i run a normal cleaning , after this that 2 channel looks more awful so i run another cleaning cycle , but after second cleaning cycle the pk and vlm disappear totally so we changed the capping station and the dampers , now the pk vlm vm and or channel doingn the same thing after an ink charge or power cleaning some lines come back but after another cleaning cycle again disappear ( sorry for my english)