MG Car Repair: 1979 MGB Roadster, brown wires, fuse box

Question
Son was driving his roadster,which had been running great.It just cut out and Pressure and fuel gauges,wipers and horn stopped functioning.AA man got it started by 'wiggling' wires at fuse box.Everything seems to be,intermittently,ok appart from horn.Any ideas please?.Brilliant site bye the way.
                            Regards Jeff C

Answer
Hi Jeffrey.  A 79 B has an Ignition relay that is powered from the Brown side of the bottom fuse.  My guess is that either the relay or the fusebox (or both) are corroded and need replacement.  This is not as difficult as it sounds, nor is it very expensive.  

When replacing the fusebox, look at the back before you fit it.  You will see a link joining two of the fuses together.  It is important that the fusebox is fitted with this link at the top, not at the bottom.  For safety, remember to disconnect the battery before you start.  

The Ignition relay is a small black (or blue) canister with 4 terminals, hanging from a screw near the fusebox.  There are two relays - the other one is for the starter motor.  The one you must replace has two brown wires, one black wire, and one white with a brown stripe.