Seiko Spare Part 315200 (315-200) – Balance Staff for Caliber 6LL / 6F / 6P / 6FA – Seiko "Merit" & "Fashion" (1 piece) – NOS

Original Seiko balance staff (天真 / Balance Staff), part number 315200 (315-200), from new old stock (NOS). This listing is for a single piece, taken from an original "SEIKO WATCH PARTS" pack ("12 pcs."), which assigns the part to the "Fashion" (ファッション) model series.

The staff is intended for the early Seiko calibers 6LL, 6F, 6P, and 6FA, which share this component. These letter codes date from before the introduction of four-digit caliber numbers and can be found on watches from the "Merit" (メリット) and "Fashion" (ファッション) series – small hand-wound models from the 1950s, typically with 17 jewels. Characteristic of this era is that the movements themselves often do not bear any caliber imprint; identification is done via movement dimensions and spare parts lists. This is also the reason why these calibers are barely documented in common Western reference works, and spare parts for them are exceptionally difficult to procure.

The balance staff is one of the central and most stressed components of a mechanical movement: it carries the balance wheel with hairspring and roller table, and its fine pivots run in the endstones and jeweled holes of the bearings. A fracture of the pivots – a typical consequence of a fall – or wear on the plate are among the most common reasons why an otherwise healthy vintage movement stops. Since Seiko stopped producing these delicate parts decades ago, an original NOS staff is practically the only way to achieve a historically accurate repair for watches of this age; the alternative remains salvaging parts from a donor movement.

Within the Seiko spare parts system, the 315-xxx group identifies balance staffs; the 310-xxx group, on the other hand, refers to the complete balance with hairspring (Balance Complete). This listing explicitly offers the individual staff, not the complete balance.

The part is unused. Due to storage, minor, purely cosmetic marks are possible, which do not affect functionality.

Note on identification: The model designation "Fashion" comes from the original packaging, and the caliber specifications are from Japanese spare parts sources for part number 315200. Since movements of this era often do not bear a caliber imprint, please compare the staff dimensions (pivot diameter, total height, plate/roller seat) with the required balance staff before installation.

Manufacturer: Seiko / Seikosha (K. Hattori & Co., Japan).

Warranty (used)
This is an original part (NOS) stored for decades. The limitation period for claims for defects (statutory warranty) is 12 months from delivery.

Note
Before installation, please compare the staff dimensions and fit with the required balance staff; assembly should be carried out professionally.