Seeking Seiko Bell-Matic 4006-6050 Alarm Mainspring (Part 416805)

[TimepieceTinkerer]

Hello everyone,

I recently started servicing my Seiko Bell-Matic 4006-6050 and, during the process, discovered that the alarm mainspring (part number 416805) is broken. I've searched extensively for a replacement but haven't been able to find one at a reasonable price.

If anyone has a usable spare or knows of a good source, I would truly appreciate any leads. Please feel free to reach out to me here.

Thanks in advance, and looking forward to hearing from fellow enthusiasts. Best of luck with your own projects!

Best regards,

 

TimepieceTinkerer

[watchweasol]

Hi welcome to the forum ,  have you tried the likes of. Cousins UK,  H.S.Walsh , A.A.Thomas,  Welwynwatchparls.co.uk all in the UK or if in the states. Esslingers. Jules Borel.  Time savers.  Or even. Speedtimerkollection  in Europe.

4006A.pdf

[AndyGSi]

Welcome to the forum.

Where in the world are you.

[TimepieceTinkerer]

4 minutes ago, AndyGSi said:

Welcome to the forum.

Where in the world are you.

I'm in the UK—sorry for not mentioning that in the first place! Let me know if you need any more details.

[TimepieceTinkerer]

1 hour ago, watchweasol said:

Hi welcome to the forum ,  have you tried the likes of. Cousins UK,  H.S.Walsh , A.A.Thomas,  Welwynwatchparls.co.uk all in the UK or if in the states. Esslingers. Jules Borel.  Time savers.  Or even. Speedtimerkollection  in Europe.

4006A.pdf 1.5 MB · 0 downloads

Thanks for replay, Yes I have already tried. 

[AndyGSi]

Can you confirm the dimensions from the old one as I've got it as this being an equivalent.

I presume the ones on eBay are more than you want to pay.

Edit

I've also got another note saying anything 1.35 x 0.07/0.08 x 260+ being suitable.

Edited March 12 by AndyGSi

[TimepieceTinkerer]

Thank you for your reply.

Yes, the ones on eBay are quite expensive and beyond my budget for this project. I appreciate you sharing the alternative part and its dimensions—I will give it a try and see if it works.

Thanks again for your help!

[mikepilk]

It's not listed in the GR database, or on Cousins. Try either of those suggested by @AndyGSi. As long as it fits, the dimensions aren't as crucial as the mainspring

[AndyGSi]

1 hour ago, TimepieceTinkerer said:

Thank you for your reply.

Yes, the ones on eBay are quite expensive and beyond my budget for this project. I appreciate you sharing the alternative part and its dimensions—I will give it a try and see if it works.

Thanks again for your help!

Can you measure the old one to confirm?

[Nucejoe]

54 minutes ago, mikepilk said:

As long as it fits, the dimensions aren't as crucial as the mainspring

   

Occur with mike , it is not as crucial as the mainspring, as its not a part of time keeping gear. Furthermore, doesn't have to be a new spring.

Then 6050 is refference No for the case, unrelated to the movement's  caliber.

Rgds

[Curare]

Hi,

I restored a Bell-Matic in 2023 and used the spring Andy suggested "GR40187" for the alarm spring which was purchased from Cousins in the UK

I did have an small issue which was overcome, I think it was the arbour was a lot larger than the eyelet in the aftermarket spring.

TIP: don't forget the install the washer part no: 419.805 before installing the spring

Edited March 12 by Curare
Typo

[TimepieceTinkerer]

On 3/12/2025 at 4:00 PM, TimepieceTinkerer said:

Hello everyone,

I recently started servicing my Seiko Bell-Matic 4006-6050 and, during the process, discovered that the alarm mainspring (part number 416805) is broken. I've searched extensively for a replacement but haven't been able to find one at a reasonable price.

If anyone has a usable spare or knows of a good source, I would truly appreciate any leads. Please feel free to reach out to me here.

Thanks in advance, and looking forward to hearing from fellow enthusiasts. Best of luck with your own projects!

Best regards,

 

TimepieceTinkerer

Update on Seiko Bell-Matic 4006-6050 Alarm Mainspring Replacement

Hello everyone,

I want to extend a heartfelt thanks to everyone who offered advice and assistance regarding my search for a replacement alarm mainspring (part number 416805) for my project. Your support and insights were incredibly valuable. I managed to acquire a 4006 main base, which includes the alarm spring already installed. This solution will allow me to proceed with my servicing project effectively. I sincerely appreciate your help.

Once again, thank you all for your contributions and support. It's wonderful to be part of such a knowledgeable and supportive community.

Best regards,

TimepieceTinkerer