I live in Manitoba, Canada and just purchased a dual pack of SMH10 headsets via Ebay.  When I installed them all went well until installing the second module on the helmet.  The tab that lock the module to the bracket does not "click in", when I push in and then lift up with my fingernail I can get it to latch, and then taking it of the helmet is equally as difficult.  If I do not lift the tab with my nail it will just fall off.  Only the one module is like this and works the same way on both helmets, while the other module latches in and is easy to press to remove.  is there a local (Winnipeg, Manitoba, Canada)  distributor for Sena?   Or is there a replacement back that can be sent to me?  Both units function (electronically) very well and were able to communicate and pair with my phone.  The serial #'s are 120601871 and 120601872.   The defective module ends in 120601871.