A few weeks ago, my 6yr old son dropped the transmitter while he was flying the Vapor. It was my mistake to not use the neck strap. Long story short, I just decided to live with it until I decided to build and test out the BP Hobbies Fiesler which requires flap control, which is tied to the Gear switch on the DX6i, which of course was broken.
I poked around the internet and got some hints on a replacement switch. First and foremost, I called horizon hobby and asked them about the repair and they said $15 + shipping which would be about a total of $35.
Today, I opened the box (of course I might have voided the warranty, but what the heck). I am an electronics engineer and comfortable with terminology, components and soldering. The switch was a simple Miniature Toggle Switch, Single Pole Dual Throw (SPDT). Look at the picture below for more details.
There are many such switches available at online stores like mouser.com or digikey.com but then decided to first try my luck at Radio Shack and found one was a close fit : SPDT Flatted Metal Lever Toggle Switch, Model: 275-635 | Catalog #: 275-635. I say close as the length of the lip is a tad short but enough if you remove all of the unnecessary washers and just use one nut to fix the switch to the case.
I opened the case and carefully removed the six xcrews. Next I carefully unscrewed the ring around the switch to remove it from the dx6i case, desoldered the wires from the broken switch and soldered them to the new switch. Note that the center lead is the ground and you can chose any one of the outer leads to be the signal. Push the switch thru the hole and tighten the nut. Take your time doing this and do not rush it. Replace all the 6 screws. And you are done.
Drop me a line with details of the switch you used for the repair and I will be more than happy to document it here.