Definite electrical problem. The head is getting the signal to turn on, but not getting an off signal, so it shoots ink continuously.
Normally this is down to a bad head cable, so that would be the first ( cheap ) thing to change. If that doesn't fix it the next thing to check is the transistors on the main board ( these send the on and off signals to the head ). If these are ok it is most likely the print carriage board is failing. 9/10 it's not a problem with the actual head, it is the signal it is receiving.