Fault Diagnosis Flowcharts

This lesson builds directly on the earlier Fault Diagnosis lesson by walking through structured reasoning for four specific, commonly encountered symptom categories, in the order a watchmaker would typically investigate them: from least to most invasive. A watch that has stopped entirely is checked first for power (fully run down, or a broken mainspring), then for an obstruction in the train (a displaced part, a foreign object, or a magnetised hairspring clinging to itself so tightly it cannot swing), and only then, if those are excluded, for a deeper fault such as a seized jewel or a broken pivot, which typically requires full disassembly to confirm.

Low amplitude with an otherwise steady beat generally points toward reduced power delivery or increased friction somewhere specific in the chain: a weak or worn mainspring, dried or gummed lubrication (very often the single most common cause in a movement overdue for service), a slightly bent pivot creating extra drag, or incorrect escapement geometry such as excess lock. The diagnostic approach narrows this list by checking amplitude at multiple points in the wind (since a mainspring problem typically worsens as the spring runs down, while a lubrication or geometry problem tends to depress amplitude fairly evenly throughout) and by testing in more than one position, since escapement geometry problems often show more strongly in some positions than others.

Poor or inconsistent positional rates, with amplitude and beat error otherwise reasonable, most often trace back to an out-of-poise balance or an off-centre hairspring, both covered in earlier lessons, though a bent pivot creating position-dependent friction, or a hairspring occasionally touching the balance cock in only some orientations, are also on the differential list and are distinguished by close visual inspection under magnification in each problem orientation rather than by timing-machine numbers alone.

Knocking — an audible extra click or thud beyond the normal escapement tick, often felt as well as heard — is a distinct category usually caused by a loose part striking the plate or another wheel with each rotation (a loose balance screw, a cracked or loose jewel setting, a slightly bent hand touching the crystal or another hand, or in more serious cases a cracked balance or escape wheel), and is generally treated as needing prompt full inspection rather than continued running, since a loose part left in place risks further, more extensive damage the longer the watch continues to run.

The recurring lesson across all four categories is that a competent diagnosis narrows a wide field of possible causes to a small, testable set through a deliberate, staged sequence of observations, rather than jumping to disassembly or a guessed fix at the first symptom — and that this staged reasoning is exactly what a reader should expect, and can reasonably ask about, when discussing a suspected fault with a professional watchmaker.