Roland,
I have found that replacing the fuel nozzle and/or filter in an inoperative Hurricane heater very rarely cures the problem. However, the heater is a relatively simple system so it is normally fairly easy to determine the problem with a through diagnosis.
My Hurricane has over 2200 hours and although I have cleaned the nozzle and chamber numerous times it is still running the original nozzle. However, I have had to repair the compressor twice, replace the fuel pump twice, replace the combustion fan once (yesterday), and bleed the system for air several times. So if you read the manual carefully, and carefully check the components for proper operation you should be warm soon.
Gerald