Do you mean that it breaks in the machine step, and you do not get any outputs that you can work with to have the workflow take different steps based on the result?
I have not been using the soap (web service) connector all that much, but it sounds like if that is the case, you are kind of screwed, I am afraid.
This is one of the reasons why in Connect, all of these HTTP calls are made inside of a flow script module, so you can control these sorts of things. But for Classic, sorry, no good input.
Perhaps someone else has a better answer, but that’s the best I can offer.