A thermal probe is a small device which can return data about the temperature. The thermal probes in the NZXT Hades case are very simple, so if one breaks it is easy to make your own.
Make my own?! How can I do that?
It is actually very simple. Thermal probes in the NZXT cases (and in many other PC cases) is made up of only one component: a thermistor
So what's a thermistor
you ask? A thermistor is a very simple electrical component. It is a resistor which changes resistance based on the temperature.
Get some thermistors
First you will have to figure out what kind of thermistors your case uses. After some googling around I managed to figure out that the NZXT Hades uses 10kOhm NTC Thermistors. These thermistors seems very common in pc temperature sensing. If your case is not the same it might use some different thermistors, you will just have to do some research to figure out what thermistors it uses. After figuring out what kind of thermistors your case uses you will have to buy some of those (1 thermistor per broken thermal probe).
I bought my 10K thermistors from Sparkfun. They can be found here: http://www.sparkfun.com/commerce/product_info.php?products_id=250