Not the thread I remembered but I did find this....
For what it's worth, I had a problem with a brake lever I bought on Ebay. It seemed to fit, but it became apparent that it wasn't pressing the brake light microswitch properly, leaving my brake light on all the time. It may possibly have been an explanation for another biker riding into me when I stopped, as I imagine there was no change in intensity from the light when I braked as it was already on!
Watch out for that! D