Ian, to show you just how easy it is to R&R the switch, I removed it for the pictures in less than a minute, took the pics and had it back in the car, all in less than 3 minutes. Why? Because I had it out about 10 times to get the tabs bent into the correct position last week. It takes a bit of fiddling, but it's not brain surgery. If yours are coming on late, or not at all, they need to be bent more, but only very, very slightly.
This first pic shows the brake light switch, as well as the tab that needs to be bent. There is one on top and one on the bottom. If they are bent too much, then the brake lights will be on all the time. If the tab is too flat, as they are on a brand-new switch, the lights may not come on at all.
This is a pic of the master cylinder pushrod that the switch contacts when assembled. See the flats on the end I was talking about earlier? That's what pushes the tab into the switch, closing the circuit and making the brake lights come on. Hopefully this gives you an idea of what's going on and how to adjust it so it works correctly.
The disassembly is easy, but critical. There's a clip on the end of the stud that the switch and pushrod mount to, remove the clip and there should be a 1/8" plastic spacer that slips off. Then wiggle the pushrod/switch out towards the end of the stud so it's all flush on the end, then simply push the rear of the switch upwards and take it off. Oh yeah, unplug the switch first, it'll be easier that way. When you reassemble the whole thing, please make SURE the clip is in snug, because if it's not, and it falls out, there's nothing at all to keep the master cylinder pushrod on the brake pedal, and if it fals off, you will have no brakes. Let me know if you need anything else, Jim