1978 Seiko 6306-7001 – GL831
$1,200.00
1978 Seiko 6306-7001 – GL831
Purchase Options
1 in stock
1978 Seiko 6306-7001 (JDM) — 23-Jewel Upgrade, on GL831 Strap
A November 1978 JDM automatic diver, fully serviced, regulated across six positions, and power reserve tested on the bench. Free insured shipping with signature confirmation.
Highlights
- Model: Seiko 6306-7001 (JDM), November 1978
- Originality: Original dial, hands, case, and bezel insert
- Movement: Seiko 6306 automatic, upgraded from 21 to 23 jewels
- Timing: 0 s/d average across six positions, 8 s/d positional delta
- Power reserve: 51 hours
- Crystal: New mineral crystal; original crystal included
- Strap: Original Seiko GL831
Video
From the Bench
Full movement service with a new mainspring, and jewels installed at the barrel arbor ports. The original unjewelled ports had wear and required remediation. A new mineral crystal was fitted, and the watch was pressure tested to 6 bar. The bezel insert lume pip is relumed; all other lume on the dial and hands is original.
Note: The 6 bar test is a service check only. Given the watch’s age, water resistance is not guaranteed and water use is not recommended.
Timegrapher Results
Measured at full wind after final regulation. Timegrapher photos are included in the listing gallery.
| Position | Rate (s/d) | Amplitude | Beat Error (ms) |
|---|---|---|---|
| Dial Up | +5 | 255° | 0.1 |
| Dial Down | 0 | 263° | 0.2 |
| Crown Down | 0 | 243° | 0.5 |
| Crown Up | −3 | 244° | 0.1 |
| Crown Left | 0 | 242° | 0.2 |
| Crown Right | −3 | 240° | 0.4 |
| Average | 0 | 248° | 0.25 |
- Positional delta: 8 s/d across six positions
- Power reserve: 51 hours, holding 0 s/d and 220° amplitude at the 24-hour mark
Condition
The dial and hands are clean with original lume. The original bezel insert shows scratching consistent with nearly five decades of use, along with a blue/grey fade visible at certain lighting angles, and the case shows honest wear. Please review all photos closely; they are part of the description.
About the Seiko 6306-7001
The 6306-7001 is the Japan Domestic Market counterpart to the well-known 6309 export diver. It shares the classic Seiko “turtle” cushion case and tool-watch build, but has hacking and runs on the higher-spec 21-jewel 6306 caliber, which this example takes to 23.
What’s Included
- Serviced Seiko 6306-7001 (JDM) watch head
- Original Seiko GL831 strap
- Original crystal
- Original mainspring
- Second Tour Timeworks service record card
- Listing digital picture set upon request
Shipping & Handling
- Free insured shipping with tracking and signature confirmation
- Carefully packed and boxed
- Domestic U.S. shipping unless arranged in advance
Second Tour Timeworks — restored to be worn, verified to be trusted.
