I feel most fortunate that throughout my history in designing and modifying lights early on and then building them from scratch later that there have not been any designs or assemblies that were faulty in nature or prone to failure. I suppose I can take credit for the mechanical aspects and external power and switching paths as integrated into the lights but the heart and soul of the lights being in the converters, it is Wayne and others who designed and manufactured the converters who get the credit for their reliability and service.
There have been atypical and isolated issues with every design I have worked with and most often with the converter but also most often with the problem showing up right off the bat. Unfortunately not always in my hands but sometimes in yours. It seems that the combination of solid state circuitry with simple and straight forward mechanical switching and electrical paths can generate a high success and confidence level.
Whether identified or not, there is always a reason for a failure and a likelihood for similar failures in other units based on that reason. If the reason is a flaw in design then that flaw needs to be addressed. If the flaw is a faulty component, electrical or mechanical, and not typical across the population then the solution is to replace the faulty component and carry on. I may be guilty of selective memory but I believe the latter case is one I have had to deal with on occasion but not often, fortunately.
There is wear and tear and ultimately a need for replacement of normal wear items. These days it seems that with many if not most things we buy, a failure of a normal wear component is resolved by replacing the entire device itself, especially if it is an electronic device. But this is also true of mechanical devices and seemingly rampant in most consumer goods. But my intent and hope is that my designs of these lights will allow for repair and rebuilding of them for as long as the user sees value and merit in doing so. On this note, I believe the 3S McClickie lights have an edge on the PD lights.