In the F8 grid on Terra Therma, there's a crevice that is basically a narrow upward sloping canyon. It's something that looks like you could get through. I attempted to climb through it in an assault Supernova, and I became stuck not far from the base of it. I tried to back out with no quick success. For several minutes I was trying to reverse and turn from side to side and eventually I broke free and was able to leave the area, but it took two or three minutes of constant trying before I was able to free my mech. I don't remember if twisting torso or twisting legs is what got me loose. By the time I broke free, I was pressing several keys, so I don't know which combination actually freed me.