I lost the spark arrester bonnet and would like to purchase another.
Hi there. I looked online and I could not see what exactly you were referring to - is it the longer stack that we see on the European models? I had to replace one on a HOn30 model to make it fit for a kitbash. I ended up making one with spare parts (plasting tubing that was drilled and filed). Buying a model for spares is an option (only for deeper pockets).
20201231_114957 on Flickr
Perhaps by bumping this message up you will get other answers.
Simon