Hi. This is my first thread here. Until now I have only commented threads open by other, but now I am lost about the way to go to restore this stove. So yes. It looks like 111 roarers can also underburn. Go figure! I bought an Optimus 22 from the early 60s. The right roarer burner is the one with more wear and it underburnt with a huge orange flame. I assumed that the jet had to be changed. I have not changed the needle as it is almost new. I have not trouched actually. I have changed nothing else in this burner. With the new jet, the right bruner has improved. Now the flame is smaller. However, it still underburns when it is at maximum power or the cleaning needle is almost out. It does not underburn most of the times when simmering or at medium to maximum power, I mean with a flame that is just smaller than maximum. It does not underburn when the flame has the size of the left burner. Also, despite having the new jet, the flame at maximum power is still bigger than that of the right burner. The right burner has a jet that is not old either and it always has a blue flame, much like that of my Optimus 111 roarer. I noticed that the underburning has nothing to do with wind. It has nothing to do with high or low pressure. It does not underburn at low pressure when the fuel is extinguising! It has to only do with being at maximum power. Otherwise, the burner provides a very blue flame, except when it start underburning. Then, when underburning, suddenly the whole flame becomes orange. Any advice please?