If you have a proper blue flame at the burner why is the yellow flame a problem?
I am not trying to give you a hard time but more wondering if the unit is functioning 'well enough'. Have you evaluated NC''s advice? Could be that you have the wrong size jet in the burner. Seems that similar burners were used for alcohol, kero, diesel but the jets we different. The force 10 burners are the similar or maybe identical to burners made by others such as Svea / Optimus. There are LOT's of parts around for the old Optimus/Svea/Primus/Radius.