Where is reservoir to add fluid for the hydraulic jacks

ON my Monaco, if the bong is not going off when the jacks are retracted, you probably do not need to add fluid. The way it is added is to lower ONE jack 5" and if the bong is going off, they might be a little low on fluid. Then you slowly add fluid until the bong stops. This insures that when any of the jacks are still down more than 5", the bong will be sounding.