> how come only a range of models are affected? Aren't they all built in the same way? Most manufacturers will dual-source component suppliers (because a) it c

> how come only a range of models are affected? Aren't they all built in the same way? Most manufacturers will dual-source component suppliers (because a) it can drive your costs down, and b) you're not reliant on a single company to supply you), so it's very easy to have some models impacted but not others. Even with a single supplier you can have bad batches of raw materials, a single factory line with an assembly defect, or the QA team just happened to all be out sick one day.