Second time I’ve had a stud thermistor come apart like this. They’re convenient, but I won’t be using them anymore.
Yes they fail rather often - prefer the newer e3d with the screw and cartridge
Was it potted in there?
Yeah, its some sort of black epoxy into the head of the stud.
Told you so 
You could drill and tap the brass fitting to accept ceramic set screws
Axial-lead thermistors are best for hot ends, because they can’t come out of the block without going open-circuit. I don’t understand why people keep trying to find ways to make radial-lead thermistors a little less likely to fall out and cause thermal runaway when axial-lead works so well.
@Whosa_whatsis , do you have any pics or instructions for installing an axial lead thermistor?
It’s pretty much every hotend you find come with some bead thermisor, which is not ideal.
@Whosa_whatsis totally agree… its just a matter of drilling through the block… I had been using axial thermistors on my home made hot ends back when i had a prusa i2…Even the pins on a axial thermistor are much harder to break .
@Panayiotis_Savva The block has to be designed for it, or you have to modify it. Most heater blocks are fairly easy to drill a 2mm hole through for a Honeywell 135-104LAG-J01.
That was, BTW, the ONLY good thing about the budaschnozzle, which IIRC was the first to use the honeywell axial thermistors.