HP 950 printhead received from the customer but nothing able to fix for initial check up

customer sent 3 hp 950 printhead for repair, but ibfound out all 3 printheads are not able to fix when I do initial check up. reason for non fixable 1. black sludge sat on top of the mesh which takes very long time for dissolve the sludges 2. all color nozzle already totally dried up by air exposed. 3. chmaber wall broke , magenta nozzle broke,