I understand that the cal 330 bumper has stop springs located on the center bridge to help cushion the rotor as it rotates. I have a Seamaster cal 2757 that utilizes a cal 355 bumper movement that sounds as if it makes a hard stop on the center bridge. However, unlike the 330 I see no spot for stop springs to attach on the bridge. Did the 355 not use stop springs and hence the hard stop or am I missing something here?

 

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Omega_330
http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Omega_355

The 355 springs are hidden.

 

Thanks @Bill Sohne and @Vercingetorix. I assume they are hidden under the center bridge? Unfortunately I have a blurry material sheet and thus unable to tell what part number these 355 stop springs are.

edit: part 332-1415

 

Bridge 1013 in the parts list above sits on top of bridge 1009, and is held in place with screws. There are two “box” shaped coiled compression springs (part number 1415), one of each that fit into each of the two rectangular slots in bridge 1009. Those are the bumper springs that stop the rotor at the ends of its swing. When the watch is all together, you may not easily see those springs. But especially if they are not there.

 

For future reference.

 

The movement on the right looks like a 28.10 RA SC - like the 350. On this movement the springs are not hidden.