Re: My Mule is now dead.
If it is a FluPIC engine, you'll need someone else to fix it. Don very likely won't work on someone else's light engine. He's not really into modding his own lights, much less the work of others.
On the other hand, you can very easily order a new light engine from Don, and that will run around 130USD plus or minus something. That you could do with a simple ordering email the same as with a light. Just put 'LE only' in your subject, and order away (specifying 3V or 6V, LED, etc.).
The highest possible drive current is 3A on a FluPIC I believe, so if you were running a full power FluPIC on an LED like an SST50, XML, or maybe even running 1.4A on a XPG, overheating is easily possible when left on. If the person who built then engine did not introduce an extra heat sink, then for sure HIGH was only meant for burst and not for long run times.
I speak from experience as I have gathered and had modded several FluPICs, and these light engines when running in the full range can really burn. Without extra precautions in terms of use habits and/or extra heatsinking, a FluPIC has more than enough drive current to burn an LED on extend runs.
obi