Nozzle melted out of the isolator guide

I have bought my 3d printer 2 weeks ago and just completed the assembly, but with lots of challenges. I got the printer to the stage were I need to load the filler material but my 1st attempt the Isolator guide melted before the filler material started to move to the nozzle, I swapped the 2nd isolater guide with my 2nd isolator and it happened again. Lost 2 isolater guides without the filler materials being fed to printer head. I have measured the temperature of the nozzle and compared it to the temperature on the screen and the nozzle is between 25 - 30°C higher than on the screen.
Please can you assist

This is probably due to a badly mounted temperature sensor.
Please check the placement of the temperature sensor

Best Regards
VEL337