Thanks Ironman, I did not notice that post, yep, the details of the oil burner are at that post.
I used my propane burner again yesterday.
It started the oscillation and then burning in the burner tube, and I had to remember to close the choke down quite a bit to start it.
As I said before, this type of propane burner is very sensitive to choke position.
I have to start mine with the choke open about 1/4".
Once things start to heat up, I can increase gas pressure and open the choke a relative amount.
If I open the choke too far, the burner goes unstable.
But with the correct choke opening, the burner should work fine and not blow back into the burner tube.