The thin aluminium box which contains the gas fire with the electric unit behind it has two projections, one on each side, right down close to the floor. The bottom of the fire front sits on them. Higher up there are two bent wire spring clips. They go into oblong holes machined into the fire front. If the spring clips are in the correct position, they should hold the front in place, and to remove it, it requires a tug. Unfortunately the springs get bent and don't hold the front securely. Owners often put a small screw through the top to hold it in place.