Another JDM Sports Seiko for your delight today! This one is known as the ‘Basketball’ due to the fact it was designed to time basketball and football (soccer) matches with its graduated rotating inner bezel. I can only guess it was designed for college basketball games as they have two 20 minute halves and the inner ring on this is graduated in two yellow 20 minute sections with a ten minute break in between. The soccer section of the ring is marked in white blocks for 45 minutes, the time for each half of a game. It’s powered by the calibre 7017a movement which is an automatic, 21 jewel, 21,600bph, day/date movement with a flyback chronograph feature. The way to time something using this is to line up the inner ring with the minute hand then start the chronograph running, you can then read off the elapsed minutes against the basketball or soccer timer. Flyback means you can reset the seconds counter to zero without actually stopping the chronograph from running. This example arrived in a non running state, the date wouldn’t set and the chrono seconds hand wouldn’t move or reset.

On the horseshoe style caseback it has a production date of April 1970, it also carries the ‘Waterproof’ script on the back and dial. Due to a tightening of regulations in the USA this was changed around this time to read Water Resistant so if you hear of people talking about Seikos with ‘Proof” and “Resist” casebacks and dials you’ll know what they’re on about now (if you didn’t already)!

With the caseback removed you can see the calibre 7017a movement, the 7 series movements ran all the way through Seikos line right up to the 7S movements which are only just being superseded today with the NH series.

With the movement uncased you can see the lovely dial and handset.

Underneath the dial is the day/date rings, these are quickset by rotating (date) and pressing (day) the crown. Because this is a JDM model it has the kanji language option on the day wheel.

Below the day wheel the calendar top plate and day change finger can be seen….

….and with this removed you get a clearer view of the calendar side components.

The plate’s stripped bare in this shot.

With the movement turned over you can see the typical architecture of a calibre 7 series with it’s exposed magic lever and transmission wheel. You can also see the extra 4 jewels on the escape and third wheel pinions.

Once the autowind mechanism and balance assembly is removed the main bridge can be removed.

This then exposes the chronograph layer, a very simple setup. Interestingly, at the top of the movement you can see a hole, this movement was the based on the 17 jewel 7016a which has a 12 hour chronograph feature. The minute and hour registers on a 7016a share the same subdial and that hole is where they live. If you’re observant you can also see the reason the chrono seconds hand wouldn’t run or reset – answer provided later on!

With the levers and springs removed the train bridge is ready for removal….

….and once it is you can see the train layout below.

With the barrel and wheels removed the problem with the date setting is revealed, the stem has snapped off in the plate and is wedged tight. The centre wheel can’t be removed until I can extricate the stem section.

With a Heath Robisonesque press made from stud extractor and a couple of old screwdivers I managed to remove the offending part. It was bent in the middle which explains its reluctance to come out.

This meant the movement was now ready for cleaning and inspection.

Referring to the earlier question about the seconds not running or resetting did you spot the problem? The tip of the chrono centre wheel had been broken off, luckily I managed to track down a NOS example. I think this particular watch must have suffered a knock or been dropped onto a hard surface at some point to cause this sort of damage with the wheel and stem. The other problem with the movement that was spotted at inspection was very worn balance pivots and damaged hairspring.

I began the rebuild in my usual way with the mainspring.

The train was built up….

….then the chrono layer….

….then the top bridge.

Although the balance was worn and the spring misshapen I thought I’d see if it could be brought back to health. It was polished and fitted and adjustment was attempted.

Unfortunately when on the timegrapher it was apparent the amplitude was suffering and the positional variation was terrible no matter how much adjustment I carried out so the balance was replaced with a new one.

The calendar side was built up….

….and the dial and handset refitted. A further problem was that the day wouldn’t change smoothly when the crown was depressed. Even with the new stem fitted the set lever was slipping out of it’s groove before the day changed so a new one was ordered and fitted, the bottom of the day wheel and the central c-clip were also poilshed to help smooth the day rings action.

This left the case to tackle, the pushers were very sticky and the crystal needed replacing. The pushers are of a different construction to the 6 series types as these ones are held in the case with circlips. The pushers looked quite straight so the problem lay with the case tubes being hammered by the pushers over the past 45 years. The tubes were broached smooth again and all was good once more.

The case was stripped to replace the crystal.

All the case components were ultrasonically cleaned before it was reassembled with it’s new crystal.

The movement was recased and the rotor replaced….

…a fresh caseback seal was fitted which meant it was complete again. You won’t see too many of these Basketballs out there, a very quirky JDM model indeed – but lovely all the same!

A final shot with the chrono running and all the replaced components.