Identifying shock spring for an FEF

[Ishima]

On the off chance I wondered if anyone would be clever enough to figure out which incabloc shock spring (lyre style) the FEF 6620 uses, I tried to figure it out myself but perhaps because I've not had to track one down before, i didn't get very far. I have some very vague measurements (could only measure the good spring, in the setting) I believe it's ~1.7mm width by 1.1mm length. 
Trying to avoid buying a balance complete for the sake of an incabloc spring. 
http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&FEF_6620

Edited October 22, 2017 by Ishima

[Ishima]

correction the width was ~1.6

[mikepilk]

Hi Ishima

There are references to FEF on the Incabloc website : http://www.incabloc.ch/en/pieces_rechanges.php

From  Ranfft it looks like it should be the 6632 family on the first line. 

The upper spring is the second last column : 975.03 

[mikepilk]

Correction.

I found data on the actual cal 6620 on the Cousins website. The spring is 270.03

[Ishima]

thank you! amazing! i always forget cousins have these sorts of documents.