I de-canned my NUBM44 using the Thorlabs tool, I think DTR used to have some photo's up on the web on how to do it with a small vice and pliers, can't find it now though. I am really thinking some of the glass is just being damaged by the intensity of the light when these diodes are pushed beyond specified maximum output, some of them failing, some of them not. I have other multi watt diodes this has not happened to, it seems this failure is common with this particular diode, why not for diodes just 30% less power? If contaminations are the main culprit, you should see them failing too, but we don't see that very often, but these diodes, quite frequently.