You can also remove the camera, power up the st-16 and the aircraft, (No Props) flip the H up side down and operate the landing gear up and down.
Like Billy suggested there are 2 hex screws (2mm I think) holding the gear in place. Remove the screws pull straight down, clean the contacts and put it back together.
Here is a good video of someone taking the H apart to repair his camera, but you can see how the landing gear come off. Watch from the 9:00 minute mark on is where he removes the landing gear.