Root cause analysis of the error should occur before any decision is made. Procedures, training, quality control, communications, human engineering and management of those systems should be addressed prior to assigning fault. If the tech is dismissed, are you setting up the next one for failure? Why aren't the rest of the techs making this error? After the Root cause has been addressed, corrective action and an effectiveness check(of the corrective action) should follow. The system is only as good as the weakest link in the chain--unfortunately, the tech is the most visible when errors occur. If the tech is at fault, disciplinary action should occur according your written policies in the department or with HR involvement(keep the lawyers out of it!).