See service agents for Accucraft or other similarly distributed makes in the US. Check out the model boat world as they tend to use similar gas poker fired boiler set ups for their live steam operated kit, used in most supplied 16 mm and Fn3 scales. Again other methods of heating boilers can require different skill sets, e.g. coal or meths (pot boiler) firing have very different boiler design requirements with the addition of the need for axel driven water pumps and water tanks. Then there are ceramic burners, although gas fired their set ups end up being a hybrid of coal fired designs and skills. Contact original maker, if available, is best bet always. Max