SN is H-11951-3, The black hose looks to be the same size/material as the black hose going to the brake Reservoir, I'm not sure if runs to some type of value or switch under the larger front board? I check the Reservoir it was half full , i topped it off now... as for the electric switches my meter showed that when they are pressed they allow current to flow thru so I just assumed they are both good.. Is that black hose, what appears to be a brake line under the front panel a "Pressure Switch" of some type ? thanks again for all your help on this... frustrating