MG Car Repair: Question 1979 MG Midget Brake Pressure Switch, differential pressure, pressure switch

Question
the brake pressure switch is plastic and has a slot in the threads.  it leaks out the switch.  is there supposed to be an o-ring or gasket on pressure switch?

Answer
Hi Tony,
The differential pressure warning switch is not suppose to have fluid available to it. The operating piston inside has "O" rings that seal the fluid away from the switch. When fluid is leaking out it means the one or both "O" rings are leaking out into the switch area so you must either put a "O" ring kit in the unit or replace it. The leak has nothing to do with the switch itself.
Howard