Yes, there is a tool located on the clean grain elevator that is used. Just slide the tool on and pull it forward. It is spring loaded so it will take some force.
Keep clear of the door and hinge point when you trip it open, I worked for a guy who messed his hand up severely while opening the concave door on a C2, got it pinched real bad, OWWWWW!
if my memory serves me right you actually push the latch back to open the door. it pivots on the rear concave.and the door pivots on the front behind the countershaft
To open the door put the lever on the handle and push it back with your foot. This way when it opens only your leg will get covered with trash. The lever will end up under the axle. To close it you might have to push up the door and hold it while you get the latch in position then attach the lever and pull foward. Hang on to the lever until it is completely latched or it might pop off and rearange your teeth.