Context changes the requirement
Following a prescribed component check is different from investigating an intermittent fault with several possible causes. Both may involve diagnosis, but the judgement and evidence required differ.
Stay close to the role
Define the tasks a technician is expected to perform and the required level of competence. Do not give an advanced diagnostic activity to a role whose work only requires a defined inspection procedure.
Assess the right actions
Build practical activities around the selected profile and task complexity. Observe how the technician follows the process, interprets evidence and confirms the result. Avoid reducing this context to a generic score.