Not sure re the part you need, but it usually is just a loose or missing torx head screw.
Re the bowden cables, I pop the panel out (LH side, you have to release the clip at the side by reaching a hand in behind after removing a side panel or two first). Then you just waggle it around (without too much force) until you get the end of the cable in place. Then the cable clips in. There is not much slack but it always works out (tightly) for me. Are they correctly routed to the back of the panel?