Have you ever considered a career in foot modeling Walter? You may get some offers after that post. I must say I was too distracted to notice the valve, but now that I see it, that's a great tool. Most Marklin boiler threads match one of the US fractional fine threads although I can't recall which one at the moment. I've never tried pulling out a dent but have always done it the hard way by opening up the boiler, but that's really difficult with many Marklins which have silver soldered flues.