You can get all the GE manuals, even the service manual here.
I know the password for the Logic 9 external service is gogems.
Here's some info from the Voluson Manual
1.) If not already in read mode, FREEZE the image.
2.) Press the UTILITIES key on the control panel and touch SYSTEM SETUP to invoke setup desktop.
3.) On the left side of the screen select ADMINISTRATION and then click on the SERVICE tab.
4.) Enter the password SHE and then click the ACCEPT button.
5.) Click the CSD button.
6.) As soon as the GEHC Service Home Page appears, select “Operator” from the pull-down menu,
enter the password uls and then click [Okay]