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Jw Benson winding stem removal

Daveb

By Daveb
in Watch Repairs Help & Advice

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Daveb Watch Enthusiast

Daveb

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Hi, I'm trying my hand at working on watches for the third time, hopefully third time lucky. I have a J w Benson pocket watch that doesn't run so I will try and fix it. I have already hit a hurdle, I can't remove the movement from the case because a can't find how to take the winding stem out. I have tried removing the screw on the left of the crown wheel but it doesn't do anything. I think it's a cyma 939 movement if that helps. If anyone could help I would be very grateful ?

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oldhippy Distinguished Member

oldhippy

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Let all the power off, make sure you have the bezel removed, You don't need to remove the case screws as I see in your photo there not there, pull the winding button up as if you are about to set the hands, you should be able to remove the movement from the case. 

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Daveb Watch Enthusiast

Daveb

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9 minutes ago, oldhippy said:

Let all the power off, make sure you have the bezel removed, You don't need to remove the case screws as I see in your photo there not there, pull the winding button up as if you are about to set the hands, you should be able to remove the movement from the case. 

Thanks oldhippy, it's out ?

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Daveb Watch Enthusiast

Daveb

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Ok, movement all stripped down, as I expected it has a broken mainspring.  The ranfft database lists it as 2.95 x 17 x 0.19 I can only see 2.9 or 3 mm on the cousins website, I have found a used one but don't have a mainspring winder, is there an option of a different size? Many thanks

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oldhippy Distinguished Member

oldhippy

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If it is the difference of one size it will be fine. A tip to remember. The spring in the barrel should take up a third of the space, the other being the arbor and the gap between the arbor and the spring, if you follow that you won't go wrong.  

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