Electrics gone haywire ! Options

[63acornwall]

Yesterday was like a normal day . I started up my 914/6 Tribute ( original 1975 914 with a 1974 911 6 cylinder transplant running on Webers ) , ran down to the fuel station in daylight , turn indicators work fine . Came home and discovered that ;

horn does not work
clock does not work
sidelights do not work
headlights do not emerge ( but high beam indicator light does)
hazard lights do not work
windscreen wipers do not work

What does work is ignition light , starter , and turn indicators

Had a look at the fusebox which is aftermarket with blade type fuses , random checked a few fuses eg headlamp motor , parking lights - all ok

So I guess there is no power supply to those circuits into the fuse box if fuses OK

All I can think of is that some multi lead part of wiring harness has come unfixed but where do I look , I dont fancy pulling spaghetti out in case car ceases to work altogether !!

Advice please - my specialist is 80 miles away but will drive it there as a last resort