I received a rad, grated it had to come across an ocean, from Spares and it arrived damaged. Not to the sensor but the filler neck...still, worth a look around to confirm there is no external/internal damage from shipping. These days, it could just simply be a manufactures issue. I have had too many of those to count!!
Thanks. Good to know I'm not alone. I had some feedback from the supplier. They were and are very helpful people. The advised NOT to fit the seal to the sensor before inserting it into the radiator hole. They advised to put the seal in first, separately, then the sensor, then the retaining clip. I thought, fair enough, it's worth a try. I also wrapped PTFE tape around the sensor to make a tighter fit between it and the seal as it seemed a little loose to me. So far, it's holding water, but I'm watching it like a hawk.