So, after running the tube forge for a while, I had a problem. Basically, the heating coils got too hot and started to melt/droop around the quartz tube. The coil ended up pooling at a the bottom of the forge, shorting, and burning out. I ended up fixing this by re-building the coil and this time - stuffing it full of clay! The idea is that the clay will bake in-place and form a hard ceramic that will act as a support for the coils - keeping them in place.