Here is a fishbone diagram put together by a motor manufacturing team addressing a high failure rate on an in-house test. This particular test (cycle destruct test) was an early indicator of motor performance in the field.
The team got together and identified thirteen potential causes that were grouped into six categories (click on the image to enlarge in a new window, and see the templates page for this file).
As an added step, the team then highlighted the fishbone diagram with the causes they suspected were most significant (highlighted in red):
Oftentimes the same causes will re-surface over time (after they have been “fixed”) due to inadequate process controls, and the team will have a fairly good idea of where they need to focus their attention.