Well, I did the thermal treatment on Y and it didn't overheat and the heatsink got a lot hotter, which is great. I then did the same job on the other axes and put them all back (in different order, probably), this time the Z failed. Now I've heat-treated a spare and swapped that in, so trying again.

Ultimately I'd like to actually buy a real TB6600 controller and try that, anyone know of a good supplier for those? Not seen one in the UK yet that looks pucker, but Far East will do!

Thanks,
Phil