Freeze the Mella at a precise location in order to jump through the crumble block, then wall jump up the long channel and mid-air morph to get out. One normalized way to do this: Kill the first two Mellas, moonwalk to the right until the third Mella just barely goes off-camera, fire a shot, and move left to scroll the Mella back on-camera just before the shot would despawn, in order to freeze it at a specific height. While it is frozen, kill the remaining Mellas, and press against the wall of Speed blocks. Perform an action that changes Samus' pose (e.g., press an angle button, jump, or crouch/uncrouch) in order to be able to moonwalk from that position. Moonwalk backwards 5 pixels, then jump straight up, and continue holding jump while pressing right, to perform a buffered turn-around spin jump to the right. If executed correctly, the Mella will move horizontally left and will be at a good height to be able to freeze and clip through the crumble block with a crouch jump. Get on top of the Mella with a mid-air morph, position under the crumble block, then unmorph for the crouch jump. Quickly spin-jump to re-enter the shaft after breaking the crumble block. Tip: if Samus moonwalks back further than 5 pixels, press against the Speed blocks again before trying to moonwalk back again, to avoid possibly getting bad subpixels.