loony888 - The plastic cover has a lowered central section which is meant to pass beneath a metal tang on the frame. This tang allows the tank catch to locate. Simply raising the plastic cover on spacers/washers would mean it will obstruct the catch. Your cover must have had the central section removed?
851neal - The rectifier on my bike failed whilst sitting at a red light in Stanhope last summer. It was during Stanhope Fair - which practically closes the village - and I sat at the red light for ever. It was a warm day, and the heat from beneath the tank was immense. By the time I moved off, I was worried. Sure enough, the first time the engine slowed to a tick-over, the generator light came on.
Steve