Optimum 96L doodlebug

Got a new to me 96L

Played with several 00 size by several different manufacturers but never the baby size.
Cleaned it up and new set of seals etc.
But noticed whilst using it that it burns with an almost buzzing noise unlike the usual burner roar. Is this just a feature of the smaller vaporizer or an issue. I kinda like the sound but it put me in mind of a pulse jet ie V1 doodlebug

 

That is unusual.
Is the brass gauze in the riser tube?

 

Yes and I did push it up to the jet end