Position one on the ignition switch your tail light should only light up when the brake is applied.
Position two the brake light should be on and the brake should get brighter when you apply the brake.
Quick question - do all CT70's have a 2 position ignition switch? Mines a 1979 and I'd swear that mines either only ON or OFF instead of having three settings: OFF, Position One, Position Two.
In the meantime, Kobwo - any luck solving your problem?