Sena are pretty busy so you may have to wait for a reply on their support pages.
Here's (some of) what they said to me:
Adam Puk
Tristan,
Any updates regarding the noise in my monitors? I had heard on the support forums that a hardware change is necessary and I need to return my 20S units in exchange for improved hardware. Is there any truth in this?
Regards
Adam
August 05, 2014 11:18 PM
Tristan
Sena Technologies
Hello Adam,
The issue was attained the main unit. The issue is, our warranty office is in the US. So please contact your reseller to get a replacement. We can get a replacement for you, but there would be shipping charges incurred to you and it would be time consuming.
So any unit with the serial number start with 1407 will have this fix.
Regards,
Tristan
August 06, 2014 02:19 PM
Adam Puk
So let me get this straight. My unit ends in 1406 so needs replacing with a 1407 because the original product is actually not fit for purpose? I am expected to do all the leg work in getting a replacement because your product is not working properly?
I didn't realise I was paying £420 to be a beta tester for Sena products, and I am less than impressed. What happens if the 1407 needs replacing in the future with a 1408/9/10 to fix the FM radio issues etc?
August 07, 2014 01:34 PM
Tristan
Sena Technologies
Hello Adam,
That's why I recommend to contact your reseller to avoid the shipping cost and time. As much as I do wish to help you and get everything working well, I am limited to what I can do.
Regards,
Tristan
August 07, 2014 01:40 PM
Turns out the units marked 1407 are manufactured in July 14, so 1408 will be August 14 and so forth.......