New thermistor isolation, how? We are trying to repair an Ultimaker Original+. One problem is a missing resistor isolation. The Ultimaker Original+ prints with up to 260 Degree Celcius. **Which kind of isolation products are suitable to resist the heat and are fitting on the thin wires of the thermistor?**

The most common choice for insulating thermistors is glass fiber sleeving. It tolerates very high temperatures, and is commonly rated for up to 600 °C.

Teflon is also used but has a rather low upper limit on its working temperature; it shouldn't be used at temperatures exceeding 260 °C - which rules it out for your purpose.