Longines 12.91 centre second help please

I need a little help with this 12.91 centre second Longines I’m trying to get going.
As you may be able to see the wheel over the 3rd that drives the centre second pinion is missing.
I have been lent some wheels that are so close but not close enough.
A wheel with 8.9mm nearly touches so I’m estimating that the wheel is 9mm to 9.1 with 75 teeth.
The pivot hole is 0.2mm but smaller or larger would be fine.
If anyone has a spare wheel from a 12.91 or 12.92 and want to sell it that would be great or a wheel with 75 teeth and 9.0 t0 9.2 they would like to sell me.
Also if one of you have a 12.91 in your collections can you accurately measure the wheel for me ?

Gerry

Ok I've sourced another wheel so that bit is fixed.
Does anyone have any details as to which balance spring was fitted originally...... over coil or flat?

Nice little project you got there😀 According to the 1928 spare parts catalog both flat and breguet
were available. Hope this helps.



Source: https://www.vintagelongines.com/#downloads

Thanks for your thoughts, I have a triangular stud, also the regulator pins are further away from the cock when its a flat spring so I'm going for a flat spring. The spring was not breathing and while I've got it so that its got amplitude I didn't want to change it anymore until I was sure which spring I was dealing with.

I have too many projects I think. Thanks for the link thats interesting