"There is no such thing as the intermittent fault. In reality it is a fault where a complex set of parameters need to be correct for it to occur"
Eh! What is this guy on about? Simple. The reason intermittent faults are just that i.e. intermittent, is that there is more than one factor at play. When all factors 'line up' the fault condition can then occur. It only takes one factor to not be correct and the fault will not manifest.
In the software game they call it 'bugs', that being under a certain set of conditions a program will or will not perform an operation that was or was not intended. The same happens with 'intermittent faults'. Got the idea?
The two common factors are either movement or temperature (which translates into movement through expansion and contraction).
The problem with 'intermittent faults' is trying to find out how many parameters are at play, and to then find out what each parameter's value (or state) needs to be in order for the fault to manifest itself. Sometimes the fault can be located in a shorter time just by trying to "make things happen" rather than spending time (often fruitless!) trying to determine all the parameters.
One thing that can be said about such faults is that time has proven for temperature to play a significant part, and is about the best advice that can be given on the subject.