MUTOH VJ-1204 print only 2 Black chanel, 1 Cyan and 1 Yelow,

Hi Rob, sounds like an Air issue, nothing more. Check dampers and check that no Air is in the tubbing. Put a drop of ink in orings and every tubing junction. Refill all the circuit with ink and try to print . If It prints, but stop those colors while printing or after sometimes, u have an Air problem (we Will check more things then). If the problem is still there with all the tubbing ok and full of ink, then head was probably damaged (that fuse that blowed usually breaks transistors on mainboard but no head... Thats why i say probably)