I thought I saw directions somewhere in another thread, but I searched and couldn't find it. I have an aging mx-810 that's having trouble registering the "up" directional button. I believe there's just years of gunk built up in there, but I have no idea how to safely open up my remote to check. It's well out of warranty. So any advice would be appreciated. I'm not worried about breaking a few tabs ;)

The shell is split in two and just snaps together. I've used a very thin slotted screw driver to carefully pry open and then slowly un-snap the rest. Pretty easy to do just take your time.

At the bottom of the remote use something to pry it apart slightly so you can get edge of an old credit card in, then side it around popping the catches. Works on almost ANY remote out there.

Cool. Is there a particular place in the bottom that's good to start? And is there any area I should avoid starting at that's fragile?

Right above the ac adapter is great place to start, you never want to try along any part of the sides of the remote, because that's where you hand slides.

A VISA card works best, Master Card works sometimes, but don't try AmEx.