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I don't think a 14 needle is that delicate really. There should be a chart in the manual showing needle sizes for various fabric weights, check that first. It is highly unlikely that removing and reinstalling the bobbin case or the hook/race would disrupt the timing, but you can eyeball it fairly easily. Hand cycling the machine, look at the needle at the very start of its upward stroke, the hook should be at the needle at the eye, or very close to the eye, the upward stroke creates a loop in the needle thread that the hook grabs. That's where I would start diagnosing anyway. Also make sure you test with a brand new needle, you don't want a needle with even the slightest bend in it.