Seiko 6309 new mainspring problem

[Pluto]

Recently bought a new mainspring from Cousins for a Seiko 6309 (spring code GR2534X). Had to wait a while as this was new stock arriving. This is the spring their database says is for this movement.

Having fitted the spring the end was far too large to fit the arbour and would not wind. Tried tightening but the end of the spring broke off.

Has anyone else had this problem? The spring is clearly not suitable.

Is their an alternative that anyone has fitted that works?

I ended up using a spare I had but it would be nice to know what others have done.

 

[clockboy]

Occasionally a spring will have this issue. When closing always support the centre with something round. This stops too much bend and keeps it in the correct shape.

[watchweasol]

As Clockboy says occasionally these things happen, probably the end was not softened enough and therefore not malleable.  I have some times remade the end softening the spring sufficiently to punch a hole and re form.

[oldhippy]

I always would use round nose pliers for this sort of job. 

[Waggy]

I've used this in the past with good results on 6309A - worth a look.

Equivalent Mainspring ETA 2892a2.pdf

To be honest I find them better than the dedicated "Seiko" mainsprings which tend to have too large a hole in the centre for the arbour so you end up having to try and close it up (and risk breaking it) so the arbour will 'bite'. All you need to do with the ETA version is remember to flip them over when you install (coloured side of disc down instead of up) and they seem to be a better fit for the arbour so no modification required.

Edited February 22, 2023 by Waggy