When troubleshooting a system, what is the NEXT course of action if a change does not solve the problem?

When faced with a situation where a change made to a system does not resolve the problem, the most logical and prudent next step is to reverse the change. This approach ensures that the system returns to its previous state, which can help confirm whether the new change was responsible for any new issues or if the original problem persists unaffected by the adjustments made.

Reversing the change allows you to eliminate that variable from the troubleshooting process, effectively narrowing down the potential causes of the problem. This technique is particularly useful because it can help re-establish a baseline state from which further troubleshooting can be conducted.

The other options, while they may be considered at different points in the troubleshooting process, are not as immediately beneficial in this scenario. For instance, establishing a new theory of probable cause might lead to further investigations without confirming whether the change had any real impact. Implementing another change could complicate the situation by adding more variables without understanding the effects of the previous one. Similarly, performing a root cause analysis is essential but may not be feasible or useful until confirming the system's condition post-change. Overall, reversing the change is the most effective immediate action to regain clarity in the troubleshooting process.