Hello Marco,
We had a problem with E-stop when installed our Matsuura MC-760 MX3 machine.
There is an electrical circuit connecting all parts of the machine that can break the circuit if there is a failure. (e.g. E-stop button on the panel, spindle oil cooling unit, e.t.c.). The last one was a cause of failure in our case, so we added some oil in the spindle and it solved the problem.
I am not sure that the diagrams for 600 and 760 machines is alike, so
you should find an electric diagram for your machine, find this circuit and follow it from start to end.
Maybe you'll find at least what is causing the trouble.
Igor
With kindest regards, Igor Kozlov