X1 TEMPERATURE GAUGE
The current gauge, which is for the GEN 3 machines, is also suitable for the earlier versions; the fit size is identical.
The temperature gauge has no bearing on the operation of the machine, it reads the temperature, but it does not regulate it. You can operate the machine without it working.
When replacing, you need to clean out any old thermal grease from the boiler and replaced it with new grease at the end of the gauge leads. You can purchase thermal grease elsewhere, it is easy to get and typically, the small syringe is more than adequate as you only need a very small amount.
Do not attempt any repair work unless you are competent/qualified.