Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Yeah. If you can’t raise Jin, email the service desk at stirlingkit, ask for a hall switch for that model. Provide a picture with an arrow if you can, to head off translation issues.  She can probably get it and sell you one for peanuts.
Their parts catalog gets built out through exactly these kinds of requests, and stirlingkit has the most responsive, capable service desk.