I was a bit surprised to see how really badly gummed up the hot blocks get as well as the surfaces of the silicon socks. These need to be cleaned probably after each print! So the silicon socks that came with my TC have a larger hole for the nozzle and a hole for the heater screw. After ruining one of these I bought replacements with the tiny hole for the tip of the nozzle and no hole for the heater screw and the difference is significant when it comes to how dirty and gummed up the set screw for the Thermistor gets as well as the screw to hold in the heater... not to mention the rest of the hot block.