Seiko 7123A advice

[KenD]

Guys,

I am into my first quartz watch repair.  1980 Seiko, 7123A movement. 

History of the watch is crystal and second hand were replaced (twice from memory) in the 80's as a result of damage. Other than that, it's just been battery changes.

A few years ago, it started playing up.  Second hand runs fine, but not the hour or minute hands.  The hands set OK from the crown. The day and date set OK from the crown both by advancing the hands past midnight and on quick-set.  No noticeable stiffness in the action.  I have read of the same issue with this movement, only the second hand running, on some forums, but not of a solution.  I tracked down a technical manual, which I have attached hoping it may assist advice. 

So far I have stripped the movement side as far as removing the circuit block but not the third wheel bridge.  Everything under the bridge is pretty clean, no gummy mess visible. The plan now on movement side is to strip the wheel train, clean, lubricate according to the manual, and reassemble. On the dial side, I'm nervous about removing the 'snap' for the day disk (shown below). From what I can see it should just lift off and I can't imagine something that small being expanded out a recess as a normal circlip would be. The more I look at it and think about it the more I'm thinking the problem is on the dial side possibly centre wheel / cannon pinion related.

'Snap'

If it makes a difference, it appears to be 'type a' hour wheel, i.e. it is gold coloured.

I have no means of doing any electronic testing on the watch except for a multimeter.  

Any experience, advice or cautions?

Cheers, Ken.

Seiko-7123A-Service-Manual.pdf

[HectorLooi]

The circlip on Seiko day disks lift off the hour wheel quite easily. Use a pair of sharp hand lifters with a piece of plastic as a dial protector and use a wedging action to slip the lifters under the circlip.

The circlip does not grip like normal circlips and lift up vertically quite easily.

[ColdWind]

Your problem lies on the dial side, must be something wrong with the cannon pinion or how the pinion interact with the fourth wheel pinion's tube. So disassemble the movement side would not solve the problem at all. About removing the C snap I saw people on youtube pry it up using a screw driver, I prefer to use a pair of small and thin hand levers, be careful as you don't want to scratch the day wheel or damage the hour wheel's post in the process, if this's your first time it probably a good idea to put a small rodico blob on top of the hour wheel's post to prevent the C clip from entering the 4th dimension. Still if what you got is a loose cannon pinion, best option would be to find a replacement part/donor movement.

Edited March 31 by ColdWind

[KenD]

Thanks, really appreciate the input. 

That appears to have worked.  A quick test shows the minute hand is now working again.