I recently pulled the dashboard out of my 78 and in the process I removed the vacuum hoses from the head lamp switch. I have since put it all back together but now there seems to be a vacuum leak in the headlamp switch.

Without jumping in the deep end and pulling the switch apart to try to fix this problem, does anybody know anything about the internal workings of the vacuum part fo the light switch or should I just buy a new one? The headlights are permanently up at present. I can get them to go down if I join the two vacuum hoses together, so that part works fine.

Also, so does anyone know how to get the light switch knob off on a 78, it seems pretty well stuck on. I will need to do this to remove the switch.

Can you actually hear the vac. leak, or just assume its leaking 'cause the lights are'nt working? If you can hear it, and the hoses are good, then the switch is probably leaking.
To get the knob off, look on the side of the switch. You should see a small metal "button". Pull the knob out until it stops, then push the button in. The knob should come out now. I'm assuming you have the instrument panel loose, so you can get to the back of the switch.

I can hear the leak. I've give it a go to get the switch out and see what I can make of it, now I know how to get the knob off.

Cheers