This was a 'keep active' project during these difficult times. I am sure similar conversions have been done before, but this just requires a washer and Primus No. 4 silent burner caps. A suitable size washer from any hardware store will do provided it sits snugly onto the bell shelf. Sand flat all the mating surfaces to maximise thermal feedback into the lipstick. These photos were taken using a Monitor 17B tank and lipstick as the engine room, but with a Primus bell and flame plate roarer, and Primus No.4 caps for the silent conversion. (Monitor bell has a captive flame plate). With the snug fit of the washer into the bell, there was no tendency for underburn. In fact the silent burner lit normally from the priming flame. The burner bell sides are not high enough to maintain enough thermal feedback without a pan, and the burner reverts to liquid feed after about 3 mins. However with a pan or kettle on slightly longer legs, the thermal feedback is improved and the silent burner runs normally. Not sure what the benefit of a silent conversion is on a small camping stove other than making a quiet early morning brew - but it works and I kept busy and interested, and learned a bit more about kerosene burners in the process.