Thank you, Waukeen.
I've been having a known problem with the scimitar mouse, which is the side keys not working at all. I have done every other available avenue suggested via their support knowledge page and forums.. but leads back to getting a firmware from support themselves. I do also have something jiggling around inside it - but it had that before the keys went.
The fact this problem has been so long-standing.. I'm surprised there has not been a fix for this yet?
Thankfully I still have my Razer Naga mouse, which is broken in a far less annoying way at this point. I had the Razer Naga for many, many years and really love it - but as I had recently got the Corsair M70 keyboard and I really like it, nice simplicity and works well. I figured the mouse would be the same. (they need to do something with iCue though... it's a horrible way to setup actions to the keys..)