So this is, as you know, not standard ETA packaging. Cousins has well publicized that Swatch has cut them off in 2015, so there are two possibilities...
1 - this is genuine ETA left over from 2015 that they maybe took out of the package
2 - this is not ETA
I tend to think it is the latter, as they also advertise this same part for the SW500. My guess (and it is only that) is that this is an SW500 barrel complete, which is compatible with the 7750.
Here's the twist...ETA was supplying Sellita with many parts, at least initially. They were selling them the balances and some escapement parts. I don't know if that extended to mainsprings and barrels, but if it did it's possible this is also from Nivarox FAR (Swatch) but purchased through Sellita.
Thank you. Really informative answer (as always from you and others here). My experience of cousins is that they don’t tent to get a lot wrong, so if they are describing the part as ETA7750 barrel /mainspring assembly I am going to assume it’s of quality and not just a junk part of similar standards to Asian copies. I’ll use the part, and report back if I have any issues or spot anything that seems to be unusual. Kind regards Darren
In future I would prefer to purchase the mainspring if they have the correct size in stock, and keep the barrel original (genuine) part.
Those springs are going to be more difficult to find as time goes by. More and more the brands are going to complete barrels. Omega stopped selling the springs and individual barrel parts for some calibers a while back - the 2892 based movemented so the 1109 1111, 1120, and the 2500 variants. They also stopped selling these parts for all their 7750 based movements - 1150 series, 1160 series, etc.
When that was announced I bought up a whole pile of springs and barrel components - this is just some of what I bought:
I'm running out, but still have some parts in stock. Once I run out I'll have to buy the barrel completes.
I always try to use the parts over again provided that they are good - barrels though on ETA based watches tend to wear out in the notches, causing the spring to slip too much, and a loss of amplitude. Looks like this:
The sharp edges of the notches wear, and the spring starts slipping too soon...just something to keep in mind.
Cheers, Al
