Hi guys, I wrote a set of five lessons regarding the Landeron 248 chronograph, which I'm presently taking my second year students through. The lesson I'm posting here is the second of the five. It looks at disassembly of the chronograph mechanism focussing on the chronograph tension spring setting and understanding its importance. The first lesson explained how to set all the seven eccentric studs correctly, so the chronograph operates to its optimum. If someone can service a vintage chrono