Debugging a SOAP web-client

Pointers please for debugging a SOAP web-client.

We have several clients in different productions all accessing a web-service. We are trying to add another client in a new production, and its not working. The messages between the relevant Process and the SOAP web-client Operation are the same in the working and the non-working productions. But the web-service is reporting an XML parsing error to the non-working production. Here's the error as reported in the SOAP web-client Operation...

Is there any way to see the output of the web-client Operation - what Ensemble is actually sending out?

SOAP web-client classes etc generated via Studio SOAP Wizard.