An engineering approach for troubleshooting:
Troubleshooters call a "Split Half Search" or a "Binary Search" which deal explicitly with the division between quick fix and systematic diagnosis and root cause discovery. ... (Then they decided to call it Quality and define it in a standard and now its someone elses problem);
What complicates this is the Assumptions one makes and or the Lack of information and or detail provided. In addition and experienced person uses most if not all of their senses when working on a problem and if not hands on; they can be significantly compromised due to lack of feedback and sensory input. As has been said before; A picture can tell a 1000 words and add to that the loss of hearing / touch and smell and the troubleshooter is grossly handicapped. .
A split-half search / binary division; is a technique for systematically isolating the source of an issue. You start by eliminating roughly half of the items you are checking, then trying to re-create the issue / find which half the fault is in. You continue halving your search group until you find the source of the issue.
A split-half search requires applying knowledge of the product, its common issues, and the symptoms as you check one possible cause after another, in a logical order. This part of the troubleshooting process can be the most difficult and the most time-consuming. Thats why a logical and methodical plan is so important.
First split - User Vs Hardware
User errors: PEBFAG - Check for user errors in the course of gathering information, and trying quick fixes. But keep in mind the possibility of incorrectly set switches or preferences, incompatible equipment, and incorrect assumptions on the users part; take nothing for granted.
But how often do users / posters get touchy when one tries to confirm and or they dont provide teh information asked for ? managing this by text; can be daunting and fraught with danger
Software-related issues: Software that is unusable or that doesnt work with other software, viruses, extension conflicts, and mass of other software issues can cause symptoms that may look like hardware issues.
A minor distraction for most of us with coffee machines but data logging software can be an issue.
Hardware issues. When you are convinced that user error/software, a is not the cause of the issue, hardware is what is left.
Simplify the issue. Find the “problem space” in the hardware. Try to identify the functional area that the issue affects and again split the problem.
Electrics Vs Plumbing etc
Thus one then splits and works through the functional blocks untill the problem is isolated; at which stage a solution can be applied.
Note: All of this takes time and relies on the user providing good data and feedback if the person troubleshooting in not on site.
The other issue is that there are some many variables in the raw product and preparation; that all so often, a poor shot still comes back to - PEBFAG.