Hot end now not so hot

[clinton 7]

I successfully printed V1 of my project today but when I came to print V2, the print started OK but then the filament feed stopped. On closer inspection it seems that the hot end is no longer very hot. When I select the maintenance option and set the nozzle temperature to 250 degC it reports that it's at temp but when I measure the nozzle with a temperature gun it's only about 30degC.

Something has failed here but I don't know what. 

Can anyone advise please? It's an Ultimaker 2+

Edited July 28, 2018 by clinton

[fbrc8-erin 296]

Are your heater and temp sensor both firmly inserted in the brass block? 

 

Is the brass block touching the fan shroud? Has any filament gotten between the brass block and fan shroud? 

 

Are you using an infrared temperature gun or something with a contact probe? Contact is usually more accurate for nozzles because of the reflectivity. 
 

How does it feel if you push filament through by hand with it heated to 250? Is there any sign that heat is reaching the filament?